Auto Trans question

For you transmission rebuild guru's; I've got a TH400 out of a '67 Pontiac, having problems shifting. Doesn't want to shift at all until it warms up (about 5-10 miles of driving), then seems to do OK. Had somebody tell me the "lip" seals are hard and soften up once the fluid warms up. I've never done any work on an auto trans, so my question is, is this something a novice transmission guy could do? I've done my share of motors, have a healthy supply of tools and equipment etc..just never worked on an auto. AAMCO gave me "ballpark" $850-1100.00 to do the work. (trans is still in the car).

Whadya think?

 

I think it is just varnished up inside. Change the fluid and see if that helps.

 

They used to sell cans of tranny conditioner that you put into the dipstick tube and drive it and the stuff would swell the rubber seals inside the trans.Old seals get hard,contract,crack,break,it gets like piston ring end gap.So cold the seal is allowing pressure to blow by the gap=low pressure=no apply til fluid heats up which swells the seal til gap is closed then it works.Wouldn't be affraid to add 2 cans,when your driving to circulate conditioner manual shift upshift and downshift it helps free up sticky valves sometimes,good luck.