When I've seen tables have speed problems only on one speed, it's usually something mechanical. Tables with belt or wheel drives that physically change paths to change speed can have something on the surface of the pulley that causes it to slip, so maybe cleaning will help. But if you're going to clean it yourself, be careful with solvents around rubber or plastics.You might also find that the belt is stretched or the roller worn out. If it has just a little more friction on one surface than the other, that's sometimes enough to make one work while the other slips. You might consider sending the turntable in for service. Approved Audio Service is a sponsor here, so I usually suggest them. Larry is a real nice guy and I'm sure he'll be most helpful.