Ok, now I'm at a PC it's a little easier. I doubt you have any solenoid issues, especially without a code but it's not completely out of the question.
What I think may be happening is your seal on the 4th apply piston is damaged....easy to verify.
What I would do is rather simple with hand tools, get the passenger side up on jack stands and take a prybar and force that cover in, should only move 1/8 to 1/4". If it only moves a little bit, I would suspect you have a bad seal on the 4th apply piston. If you can move it in a half inch or more then you possibly have other major issues but you won't know until you pull that cover...I doubt it though.
To access that cover, you need to lower the cross member a little but it's easy, no need to remove any linkages or drive shaft, just a few bolts.
Both horizontal bolts on passenger side and the four vertical bolts come out. On drivers side, inner horizontal bolt comes out, loosen outer bolt. You can remove all 4 of the vertical bolts on the drivers side, I like to leave the outer 2 about halfway out and let the cross member pivot down.
Place a jack under the center just in case but you will need to pry it down slightly.
Don't do any of the rest until you have a new outer cover seal.
I would pick up a 4th apply piston seal as well or just get all of them. Best thing to do is purchase a vette servo and replace it while you're in there....most people do this.
Once exposed, take a small brush and clean around snap ring.
Remove snap ring with screwdriver, just pops off.
Use an angled pick and pull on seal, pull it snug and rotate cap until it pops off. Worst case you have to cut the seal but generally you can stretch it. This is recommended just in case the new seal doesn't work and you need to drive it later.
