c6 servo sticking

[GATMsport]

Morning,
I have a 84 model c6 tranny in a f250. It was leaking badly at the servo body. I have ordered the gasket and the oring.
First Question i have is:
With the servo apart i found that the piston itself only moves about 1/4 in then sticks. I have tried to pull it all the way out but have not pulled to extream, not knowing if i should. Shouldnt this move freely all way out?

2nd question:
I ordered a new piston. I had two choices. One that said it was for an "L" code, and one was for an "N" code.
There was a tag on the servo cover bolt. There was a code w an "L" in it. (PGD DL15 D120 F4TP CA)
I ordered the part based on the "L".
Was i correct?

Thanks for anyones time

[BobbyFord]

There should be a letter cast on the outside of the servo cover.
The piston should be a tight fit and difficult to move by hand.