Not too hard to check this out, Tim. Drain oil and coolant. Remove brake pedal, kickstarter and maybe water pump guard. Then remove cover and you MIGHT have to take off clutch to get at counterbalancer, I'm not sure (I'm at work, bike's at home). BTW I've had my cover off three times now with original gasket and no leaks. Don't drop/lose dowel pins that sit in the case and be careful with the gasket. As for checking it, just make sure there is no play (fore/aft or rotationally) in the gear, and I would think you could get a finger or two on the gear even with the clutch still on (the counterB shaft is at the very front of the motor). Mine was noticeably wobbly due to loose nut and buggered straight key. There is also a round mark on one tooth of each gear (small gear on main shaft and counterB gear) that need to line up. Maybe they goofed at the factory and misaligned or mistimed the counterbalancer (you never know). It is not necessary to remove the gear just to check for this rare (two 426s and counting that I know of) problem but if it is wobbly you will probably want to remove it to install a new straight key. And, of course, if it is already all loose then it will come right off. This may be a long shot, and I don't know how bad your vibes are or how you take to wrenches but it could be worth a look see. Hope this helps, and I hope this is the cause of your problems because it is a very cheap (like ten cents for a key) fix.