My windshield wipers are jerky going one direction and floppy the other. I have examined the entire system and find the bronze bushings on the transmission arms to be very sloppy. I think this at least should be addressed. However, short of calling a dealer I don't find any vendors selling these arms or bushings. Does anybody have any ideas?

Give them a gentle lube, lithium grease or something similar, and tighten then up.  I have never seen the bushings listed as separate parts and assume they are included with the wiper tranny arm assemblies.

If you can remove the bushing, you should be able to take it to a local bearing supplier and get a replacement.

These are not actually bearing bushings, more of small thin pieces of bronze sheet with stamped spherical cavities that capture the ball on the end of each cross link arm connecting to the wiper arm. They've been greased and greased with the last application a very thick grease. The only solution is replacement.