If you decide a rebuild is needed. Do it yourself.
I just rebuilt my 904 and was surprised how easy it was. I have a tiny garage with no lift and was successful. I bought a cheap trans jack from Harbor Freight with the 20% off coupon, and used no special tools. I lugged the trans into my basement for the rebuild. The only problem I really had was the pump. I didn't have the pump "puller" and wasn't able to source one, so I took some 2 ft long threaded rod and put a 10lb bench press wt on it, with some washers and nuts of course to hold everything in place, and the pump came right out. There are a lot of great videos online that walk you through every step.
Good luck!
