Jeff is on the right track (so to speak). The wheels on Mean Streak cannot follow the track curves, and this is a problem. The question of why Cedar Point doesn't do anything about it (i.e. new trains) is that there isn't a whole lot they *can* do. Trains are readily available from Philadelphia Toboggan and from Gerstlauer...and trains from both manufacturers handle curves in about the same way (i. e. poorly). Only the trains built by Great Coasters Int'l. (among currently available wood coaster trains) will handle those curves, and I think GCI has their hands full at the moment.
The one thing the park can do to improve the way the ride runs is to apply lubricant to the turns. They did that early in the season, and I know they use an anti-seize lubricant on the wheels. Trouble is, it isn't enough. That lubrication washes and wears off, and the coaster starts running poorly again. Any time you hear the coaster wheels squealing, you know that the wheels are sliding sideways on the road steel. It is an action which will wear out the rails and the wheels.
Of course, there are 1,001 reasons to NOT grease the track: the lubricant is a safety hazard to ride inspectors, it gets kicked up by the wheels and soils the train...and sometimes the passengers, it's messy, it's a difficult job...and on and on and on. But there is only one reason why the rails need lubricant: because the coaster runs better that way. In the absence of properly articulated wheel sets, as Gemini has, lubricant is the one thing the park can do.
Mean Streak's other problem is rideability, not necessarily associated with the cornering problem. The cars tend to bounce an awful lot, resulting in a jackhammer effect on the riders. This is where the hard seat backs come in. If you get your back clear of the seatback, a ride on Mean Streak is tolerable. But if you sit back, it will hurt like crazy. The solution, then, is to replace the hard foam seatbacks with the m?? ??????????? ??????????? ???? ?????????? ????? ??? ???? ????????? ?? ???????? ???? ??? ???????? ???? ???? ????? ???? ??????????? ?? ???? ??? ?????? ??? ? ??? ????? ?????????? ??? ??? ???? ??? ?????? ?? ??? ??? ?????? ???? ???????? ??????? ??? ?? ?? ??????? ?????? ?? ? ?????? ????? ?? ???? ?????? ??? ??????????? ???????? ???? ???????? ??? ??????????? ????????? ??? ????? ???? ???????? ??? ?????? ???? ?????? ?? ?? ???????????????????????? ???????? ?????????????? ? ????? ???? ??? ??? ?????? ??????? ???? ??? ??????? ??? ?? ??????? ???????????