the convertible top on my 1989 xjs closes very slowly.
any ideas?

 

My 1995 XJS did the same thing. It would go down with no problem, but upon lifting up it would really hesitate and take forever. On my car, it turned out I had a leak on the passenger side hydraulic piston. The motor/pump in the trunk was also almost empty. I did not fix the piston. I just put the motor in the "manual" position and raise/lower the top manually. I find this to be much easier since the emergency brake need not be on nor your foot on the brake.