Just left my horn in the repair shop again to unfasten the stuck tuning slide. This time it got stuck simply because I had to slide it almost all the way in for an orchestra gig. Tried to unfasten with WD-40 myself without any luck.

In the past I've been greasing the slide with vaseline and a little valve oil when neccessary, but this keeps happening and its starting to hurt my wallet. How do you guys keep your main tuning slide from getting stuck?