I don't know the technical difference between these and the Techs, but the Techs have an adjustment screw on the inside that allows you to adjust the pitch control. You might wanna open them up and look for a similar adjustment. If it is a problem of not holding their pitch, that could have something to do with the motor and then yea, they're pretty much trash.

___________________
Helping girls make bad decisions since 1979

Shouldn't be too much to replace if you need to. Ebay has xl-300's for like $40 each.

___________________