How do I troubleshoot my XKR convertible top hydraulic fluid leak?
Of course if you have green hydraulic fluid leaking anywhere from your convertible roof top hosing system, XKR or XK8, then you can check to see if the hydraulic valve, hydraulic cylinder, latch cylinder seals and lift cylinder seals are tight and nothing is coming from them. If they check out OK then you do a hydraulic hose evaluation and see if you notice any cracking in the hoses themselves. Basically whatever part of the hose that is failing (coupler, valve, cylinder, seals, etc..) you will most likely need to buy some affordable jaguar hydraulic hoses (Part number for full hose HJA8258AA) or a full repair kit (Part number for repair kit HJA8258AB).

Should I only buy new hydraulic hoses from Jaguar or are there alternatives on Jaguar Forums recommended by Gus Glikas or other reputable experts?
After market roof hoses are fine as long as you can tell they are quality made or have a guarantee on them. The couplers/fittings have to be the right fit and the hydraulic hoses themselves are made from long lasting materials so cracking or failure should not be an issue for a long time. You can order them online and follow DIY guides for Hydraulic Hose Removal & Hydraulic Hose Installation if mechanically inclined or simply find someone experienced in your area and have them replace them for you.

My Jaguar convertible roof is stuck, how do I fix it?
It could be many things all the way from fuses in the electrical system on down to the hydraulic system itself. If you hear the electrical system working when you attempt to raise or lower the convertible top then I would look under the roof components (look at your Jaguar convertible model Hydraulic Roof Manual or in your System Specs) and see if you find any of the GREEN hydraulic fluid leaking that would cause the roof to no longer move up or down. If you do see some of that green hydraulic fluid then you would need to see the top answer regarding troubleshooting a convertible top hydraulic fluid leak.

Can I buy the replacement hoses only or do I need a full repair kit?
That depends, if you have hydraulic hoses that are cracked, fraying or otherwise allowing the green fluid to escape then you might only need the hoses, but if those hoses are loose at the base fittings/couplers or you would feel more at ease replacing the entire hydraulic system for the convertible top then go with the full kit. Most of the time it is only the hoses themselves that crack as they age and weather and rarely are the connections faulty or gapped letting fluid leak from the base as well.