The other thing to look for in the FM section are the 2 hidden trimmers (10K 50K) behind the Tuning indicator light, soldered through 2 layers of flex PCB. Although these are much more accessible than the same trimmer in the BM4400....
If that trimmer is shot (very likely), no FM works.
Extreme care is required to not split the flex PCB, and not damage it from heat either.
Recommended replacements are Piher PTC10 sealed cermet units.
Also, if you're planning on doing a full RF alignmenet, IIRC there are a couple of coils which were factory set, and the Service Manual specifically cautions to NOT adjust those coils at all.
Menahem