tranny slipping into n Options

[Malhar95]

Posting this for a buddy:
It's a 7a auto 1994 (corolla though)

The tranny keeps slipping into n after driving it,
It did before 2 weeks ago, checked the fluid it was low, then after a qt it showed too much but when we pulled the drained plug it pulled only a qt out (so dip stick might be bad) then it was normal driving fine

Today the car went into neutral suddenly, fluid shows fine.
Should we drain and put new oil in since dip stock can't be trusted or could it be something else?

I remember similar thing happened to my celi but it was something to do with shift cables..

[Smaay]

are you checking the fluid with the engine running? thats how you so auto trannys

[Malhar95]

After leaving the car for 2 days, today before towingit we tried one more time,
The car drives fine until it warms up, then starts reacting, drove it to a transition shop, had to shut the car off for few seconds to let it cool down, the longer we let it cool the more ot ran. I also think it's the fluid but after we drained all the fluid, I put in what the corolla forums said 4 qts so I don't think we over filled it, maybe it didn't drain completely?

[Malhar95]

problem is still there. the shop doesnt know whats wrong, "we have to open it up and check whats damage and rebuild the tranmission,then get u a qoute estimate for repair. if u decide not to fix it, its 300 to get the car back together"

so i just got the car home. is there any things i can check for myself, i was gonna replace the tranny myself eventually but until then, and suggetions?
torque convertor? (reading some stickies, sounds like u can replace the torque conv. without removing the tranns. is that correct or am i misunderstanding? its in the auto-manual sticky when mentioning the bolts to take the torque conv off)

any tips greatly appriciated