TH-350c shift help
I think you mean the accumulator on the right side of the trans.
If so,look at the case,lower left side,right where the accumlator cover is.
There is a hole, cast in the case. With an awl,or pick,anything thin enough and stout enough,push it thru the hole.
This will force the snap ring out of the groove,so you can remove the cover and spring.
Two things...Best to use a big screw driver or bar,pushing in on the cover, to releive some of the pressure,from the spring,when you do this.
And it's real easy to cut,or damage the new o'ring[for the cover].
This is important. With the spring not yet installed,put the o'ring on the cover,see if the cover will install into the case with just a little resistance.
If so,this is how you should install it.
If not,install the o'ring into the case first,then the spring,then the cover.
Use lot's of lube.