trouble? Bwhahahaha... The clutch cover gasket swap out won't cause anything to be messed up in the clutch. WHICH cover do you refer to? The one on the right side of the bike or the left. Under the right cover is the clutch basket which is driven off the primary shaft. On your bike, I think the primary shaft is driven direct off the crank. Inside the clutch basket is a pressure plate that holds the plates closed. The plates are both steel and fiber friction. To push the pressure plate open, a long rod pushes the pressure plate outwards to take pressure off the plates and disengage the clutch. Between the pressure plate and rod is a ball bearing which keeps the rod from welding to the plate. Unless he also fiddled with any of the mechanical stuff in the clutch basket, I doubt the gasket change was a factor. I THINK your bike has a clutch cable. The cable typically will have three adjustment points. The first is at the switchgear where there is an adjuster. Loosen the locknut on the adjuster and screw the thing in so there is about 3/8" between the adjuster and switchgear. Tighten the locknut... well it is acutally sort of a lockwheel sort of thing. Anyway, there is a mid-point cable adjustment. There are a couple of nuts that can be turned to take slack out of the cable. Take the slack out at the mid-point. Last is the critical adjustment point you were just getting ready for. On the left side of the bike is an engine cover with another SMALL cover held on by two screws or allen bolts. Take the bolts out and remove this small cover. UNDER the cover is a screw and locknut. The screw will take a blade screwdriver and the locknut can be loosened with a 12mm wrench. Loosen it. NOW HERE IS THE TRICKY PART. This adjuster changes the relationship with mechanism that pushes on that rod I talked about awhile back. Some screws need to be screwed IN and some OUT. It would help to have a manual for the bike to tell you what they suggest. On all my bikes, the screw is turned in to lightly seated and then backed out about 1/2 turn. This will set the adjustment near where it needs to go. Once you have it near where it should be you can take it out and ride it and adjust the clutch to your liking by tightening about 1/8 turn or backing out the screw about 1/8 turn and then trying again till you get the position set. Then just tighten the 12mm locknut and put the little cover on and you are good to go. Remember that cables tend to stretch and you will need to learn to make this adjustment as the adjustment needs to be made just from regular cable stretching. If you have any questions about this babble, don't hesitate to ask. It aint near as confusing as I made it sound!
