You can take the top shifter off. When removing the tranny, the usual way is to lower the box and remove the shifter which remains installed, but it's actually easier to remove the center console, undo the top boot, and remove the shifter that way. There's a collar holding it it, which must be pushed down a bit, and rotated. The shifter mechanism will pop out.
However, if the tranny is not shifting well, it's really unlikely this is the problem. It's more likely the wrong fluid. I'd start by flushing the unit and making sure that you use one of the following lubes:
1: Gear lube made specifically for synchros, cannot be standard GL-5, must be synchro safe. My 99 loved this stuff and went to about 250K miles before succumbing to reverse damage from an unrelated clutch crash.
2: Synthetic gear lube, may be GL-5 if it achieves this without sulphur. I think I found that Valvoline synthetic worked well. My 95 liked this for many many miles, returning to like-new service for many years after nearly dying on GL-5 junk.
3: In a pinch, just plain 10-W 30 motor oil. When I swapped my 95 tranny (with over 260K miles on it) to the 99. it was late one sunday night and I needed it fast so I used motor oil, and it went nicely for a year, no problems at all. I was ready to flush if needed, but never bothered.
What you definitely do NOT want is the GL-5 oil that was mistakenly specified for these at one time. It will eat up the brass synchros and cause bad shifting. If you suspect that's in there now, flush it ASAP.