Thanks for all the replys to this issue but the problem has been identified and its a really stupid design flaw is all it is, I finally got to work on it the last couple of days and figured out that the reason it wont unload correctly is they both (slide valve,stop) share the same high pressure line and releif line. So due to pressure differental when we have big pressure swings and the slide valve and slide stop unload at the same time the slide valve is pushing oil into the slide stop chamber. Bad design.