I'm not going to try and talk you out of doing this, only because these convertible tops have so many issues. I remember another fellow basically posting as you have, but he added that he wasn't interested spending endless hours attempting to fix a very bad design.
Go to section B of the following instructions which will instruct on cutting the hydronic lines running from the (now dead) pump to the lifters.
https://www.tophydraulicsinc.com/bmwz4instructions.pdf