I know that transport is like thousands of the Panasonic-made transports out there. But I've only worked on one of this particular model. I replaced a head on it for a customer in the late 90's. Being as it's a HI-FI model it was worth it then. I've got to tell you I've been out of the VCR repair biz for 10 years so your photos are what will jog my memory.
Along about '86 or '87 Panasonic went with a gear on the idler (the idler is the part that swings back and forth) which met teeth on both the supply, and take-up reels. But, I think I gather from your description that there is a rubber tire in the idler (which meets with SMOOTH surfaces on both reels). So, the problem is most likely the rubber tire on the idler- I believe that's what you have described as having cracks.
You said you cleaned everything. Did you clean the idler tire? Try cleaning with rubbing alcohol. You can also try some rubber restorer. But those would DEFINITELY be 'quick fixes'. Hopefully, by cleaning the tire you can get the machine to run long enough to access any other problems and determine if its cost-effective for you to continue to spend money on it. After all you don't want to find later, for instance, that after spending $20 on belts/idler tire the HI-FI heads are shot and you only have a linear mono VCR. That would suck...
It would be best to replace the whole idler but they may be hard/impossible/expensive to find. I've been out of the biz so long I don't know what's available in parts anymore. MCM Electronics used to have all kinds of that stuff. But that was 10 years ago. I did just order some VCR and CD player belt kits from Studio Sound Electronics and was impressed with their selection of generic rubber belts. They may have a replacement rubber tire you can slip onto the idler. Then clean both reels at the point where the tire meets them with rubbing alcohol, and let dry. Don't get alcohol on the new tire.
Then, look further. If it's truly worth it to you to replace the belts/idler and as long as you're ordering, go ahead and replace any other belts. There maybe a belt on the cassette loading mechanism, as well as the capstan motor to the idler.
From that point, and this may be 'too much information' but, based on my history with mid 80's Panasonic-built VCR's there is a chance that capacitors are failing in the power supply, if they haven't already (and they probably have). And, being as it's a "switching-mode" power supply when one thing fails it has a tendancy to take out a whole bunch of other stuff making troubleshooting difficult. I would budget for a complete PS recap if you intend on being serious with this unit.
Good luck with your repair! Keep us posted!
Brian