AMI model F plays slow

I reviewed the past postings on this subject that I could find. I have cleaned the idler wheel in warm soapy water. I used a rag with degreaser to remove any oil from the motor shaft and the inner lip of the turn table. I have lubed the entire mech. with special attention to the top and bottom bearing of the motor and the turntable spindle. Stylus is new, but did the same thing with the old stylus.

Problem: Motor turns turntable at about 44 rpm w/o a record on it (I don't have a stop watch, so that is an approximation using a standard watch with a second hand). Once the record is on the turntable the speed drops to 36 rpm (again approximated with available time piece). I can put resistance directly on the motor shaft and do not notice a slowing (motor feels strong with good bearings). If I put resistance on the idler pulley while it is riding on the motor shaft it slips easily, same is true if pressure is applied directly to turntable (slippage between idler and motor shaft).
The idler pulley is held against the motor shaft with a very small spring.
Could a heavier spring be used or can a rubber belt dressing (used to make rubber belts sticky to stop belt slippage and squeal) be applied to the idler rubber to provide additional friction between the idler wheel, motor shaft and turntable.
Thanks in advance, Craig.

Craig,
You might try "belt dressing"--may work, or you may need to have the wheel re-surfaced.
I would advise that under NO circumstances, should that spring be "changed", in any way !
Ron Rich

Ron,
When you say resurfaced, is that the rubber being totally replace or just the surface of the rubber roughed up? Is there a vendor that provides new rubber for these wheels or is it necessary to replace the entire idler wheel? I will try the belt dressing to start with and I will not mess with the spring.
Thanks for the input, Craig.

Hi Craig,
As far as I know, in this case, "resurfaced", indicates that all rubber is removed, and replaced--One place is listed above, in the "new-used parts--where to find" post. Ron Rich

I tried the belt conditioner and it did improve traction, however, speed remained slow. Since I have both an model F and a G I checked the idler wheel with a caliper on the G and it was slightly larger in diameter. I transferred the idler from the G to the F and sound/speed was now correct. I was using a small radio shack portable amplifier to check the sound since I am still troubleshooting the original amp.
The model F amp was not working when I got the jukebox and after a recap and new tubes it only makes a cyclic/pulsing type hum. I transferred the model G amp over to the model F and after wiggling one of the 12AU7 tubes in the model G amp music flowed from the speakers, but this was before the speed issue was corrected. Now that the speed issue is corrected the transplant amp is not functioning even after wiggling the tubes and plugs. I will try some deoxit in the tube and plug sockets (power off of course). I will recheck all the tubes to verify they are good. I also need to check the original amp that was in the model F to see if I have any issues with the transformer output. I did not check transformer in the original model F amp prior to replacing the caps.
Thank you for the on going help, Craig.

Craig, and all,
There have been many 'discussions" of idler size as related to speed on this, and other forums.
Turntable (TT) speed (except as I will note later) is NOT related to the size of the idler wheel !
In my feeble mind, I have resolved this by thinking of an electric motor driven car.
If the motor speed is set at a given RPM, the auto will travel at a given speed. If one changes the wheel/tire size, the car still will travel at the exact same speed, if the motor is operating at that same speed.
If you equate the "idler wheel" to the car's tire, one ( at least I), can visualize this well.
Exceptions are--for the car, if the tire slips on the surface--for the TT, since unlike the auto tire, the idler is not direct driven by the motor, if the idler slips on either the motor shaft, or TT rim.
Slippage, is where the idler wheel, it's linkage, and spring come into play. One (IMHO) should NEVER "mess with" the spring !
If too loose, idler will slip--if too tight, idler will be "pinched", and cause slow or "wobbly" TT speed. The design engineers took theses facts into consideration when they designed the TT system (spring tension, "scone rubber values" included).
Unfortunately, what tends to happen when the turntable speed slows down, is one of Rob/NYC's "Geppetto friends", decides that the spring needs "adjusting", and he cuts off a loop or two--Once done, that TT will NEVER run at the right speed,for any length of time ! Ron Rich

Ok, tried the deoxit and a dental pick on the preamp tube sockets and the rca plug and socket from the tone arm and by golly the darn thing made music. A bit lacking on the base compared to modern thumpers, but the treble from the horn speaker on the top was quit impressive in volume. I have not heard these AMI's sound before since both the F and G units were DOA when I purchased them. Next will work on the G unit.
Has anybody changed the power cord input on these units before? Currently they have a proprietary plug and I only have one of the plugs. Will I destroy or diminish the value of the unit if I change the cord type? Yes, I know to some these are an ugly betty type unit, but I think they are cool looking and the mech. is fun to watch.
Thanks again, Craig

Wouldn't larger tires turning at a certain RPM make your car go faster than small tires turning with that same RPM? Much like the situation in my dual speed Juke. Wouldn't the motor shaft (constant RPM) driving either of two sized tires (the different shaft diameters) change the rotational speed of the idler wheel/platter speed?

An idler wheel is just that, an idler. Try to picture this. the motor shaft diameter, just for the sake of argument, is say 1/2" in circumference. I use 1/2" just as an example. If the motor turns one revolution, the idler just transfers that 1/2" inch movement to the turntable. I doesn't matter what the diameter of the idler is. It's just the middle man between the motor shaft and the turntable. On one of my Rowe jukes the idler was hard on the surface. I chucked it in a drill and while it turned slowly, I sanded the outer diameter. That removed the hard surface and exposed some softer rubber underneath. That stopped the slipping. The diameter was a little smaller making it run slightly more rpm. But again, the diameter doesn't matter because it's just an idler.
Hope that helps

Jack

Well... I thought I had the speed corrected, but was wrong again. I guess I should not have based the proclamation of it being fixed by listening to a slow song being played. The speed is only a few RPM off but I am unable to get it to spin any faster by doctoring up the old rubber, lubrication and cleaning. Does anyone know where to get just the rubber for the idler wheel. The local suppliers that I have checked only sell the complete idler wheel. I found just the rubber listed in the United Kingdom for about $6, but was hoping to get it a little more locally, since shipping is a bit pricey from UK. If not available in the USA I would appreciate recommended source elsewhere.
Thanks, Craig.