Thought I'd share my latest saga. My 97 XK8 convertible's top one day started going up very slowly/timing out/not getting all the way up at all despite the pump running. I also saw a little bit of fluid loss so I figured it was time for new hydraulics. So I went to Top Hydraulics and got upgraded hoses, rams, and a front latch. Life happens... so it took me months to get things back together enough to test it and Ta-Da: The exact same symptoms. Some swearing, a drink, and good nights sleep later, I emailed Klaus at Top hydraulics (they've been amazing, btw, high quality place) and per his suggestion I VERY CAREFULLY swapped the 2 (super-easy-to-break-wires-on) solenoids on top of the convertible top pump and that made the top shoot right up at full speed confirming a bad top up solenoid. I found rotating them slightly to be more effective than wiggling the solenoids to get them to come out once unbolted.

So although mine had a small mystery leak and probably needed to whole upgrade anyway, if your top works one way but not the other, consider investigating the top/hood pump solenoids as a cause. I have read that you can get the solenoids separately possibly from Cabriolet Hydraulics in FL or RoofmotorsUK but I chose to just have Top Hydraulics do a full rebuild on my pump since I love using the JagWrangler key-fob roof operation mod to put my top up and down all the time and I don't want to ever worry about dealing within of this again. Didn't see a lot on this issue so thought I'd put this out here.