I've seen a couple of Nexstars with severly exagerated right thrust, that behaved like that -- one was actually unflyable & both were replaced by Hobbico -- but I've never seen (perhaps noticed would be better) any problems with the cuffs.

Experienced pilots invariably prefer the way the plane flies without the cuffs (myself included), but we already know how to fly & how we like a plane to "feel'. I have experimented with removing & replacing the cuffs on student's planes at various points in their progress. The results are quite interesting. Totally inexperienced student pilots that show little natural ability, invariably prefer the plane with the cuffs & speed brakes in place. The same students at a later point in their flying skill development, prefer the devices removed -- not a surprise. However, inexperienced pilots with demonstrable natural ability, seem to prefer the cuffs & brakes removed, despite not knowing how they work, or what a plane normally feels like in the air.