Zenith H480W clock radio - AM works, FM very weak

[zeno]

When on FM without a station do you get a loud static OR blank sound ?
If its loud static with a weak station its probably the RF amp.
If its pretty quiet but you can get a weak station its prob IF.
Stereo light will NOT light on a weak signal.
The push buttons are trouble on these, clean them. I have the same
vintage mono Zenith & the switches are VERY touchy.
The hum is probably the main caps. Now that its quiet you hear it.
As far as the spray goes it can cause detuning BUT I dont think that is
it. Try it again when well dried.
Safe way to clean the PCB is 91% isopropyl alcohol. If its residue that
should work. When done dry it under a hot lamp.
Remove the back up battery. They do leak & can ruin a radio.
And yes most the Zenith radios of this era were made by Gold Star
to Zeniths specs. The better ones had TRF AM. IIRC yours did.

73 Zeno
LFOD !