When I push in the clutch on my 98 XJ, it will immediately go into any gear smoothly. However, if I keep the clutch depressed (I used reverse to test this since it's non-synchro) and try to shift into gear, the gears begin to clash. It never gets very bad but it does get more noticeable the longer the clutch is held down. What could be causing this? Seemed like hydraulics to me, slave cylinder bleeding down or something like that, but with the install of a new sealed master/slave set, the problem is still there.