Oh god yes, replace those bushings with bearings! Man, that must be an old tranny! The gear teeth look fine. Clean out all the old grease. Use some black grease on the gears and in the diff. Lithium grease is too thin.
Trak Power blue waterproof grease is the best, and a little tub will last you years.
on those missing parts .. first I thought you were missing the screws! But I see it's the lock washers. It could be that those screws, without the washers, are poking out the back of the slipper plate and not allowing the plates and clutch pad to mate properly. Check for that. Also, the brass bushing that fits into the spur gear wears out and needs replacement eventually. It does sound like the pinion spur mesh is tight.