I bought a Z4 knowing the conv top motor was broken. The red pulley has been detached and I have been using it as a manual which is no biggie. Recently the top is extra hard to go up and down, like something with the hydraulic system doesn't work. It takes 2 people now to lift or close it. Any ideas what it could be and an easy/cheap way to get it fixed? I was hoping it needed hydraulic fluid or something easy like that.