Grundig 2440 No-FM Problems..AM/SW Works Fine HELP!!

I recently was given a Grundig 2440 multi band radio, which is in nice shape and condition and works like new on the AM and SW bands, but the FM and Public Utility (PU) bands are lifeless. I don't have any schematics to assist in diagnosing the issue. The pushbutton band selector is pretty noisy and could use a good cleaning, but I don't even get static when going to FM or PU bands. Is there a separate tube that handles the FM portion of the tuning that might be on the fritz, or is it likely something a bit more involved? There is no 60 cycle hum, so I'm guessing the main filter caps are OK, it just seems the FM isn't getting any signal...even the tuning bars don't react in any way to a sweep of the dial.
Does anyone have any ideas where to start? I'm somewhat limited in tools...basically a multimeter and a tube tester...no scope to aid in tuning anything or signal generator to assist in tracing a signal. Thank you in advance to any and all suggestions.

You need an external antenna for FM and PU. An AM/SW antenna is built in.

I do not know the age of this unit. If it is before 1948, it used the old FM band, which was confiscated for military use during World War II. You would get nothing on such a set, because that band became an AM military aircraft band.