The only way to tell for sure, if you are getting slippage is to get under the car and wathc the linkage as someone elses shifts through the gears for you. THe symptoms you described sound like one of the ujoints are slipping back and forth on the spline. In that case you just need to find which one and tighten the nut. There are three, One is under the console in the cock pit, the next is just before the trunion bearing and the last one is on the shaft coming out of the ZF. If all of these are clearly not slipping as the linkage is moved, you will have to adjust the shaft which goes into the shifter box. If it comes to that, I will step you through that also. Best thing to do with shifter linkage is to do the easiest things first.
