What should I do if my pegs slip or get stuck?

Even normal tuning will cause both pegs and the peg hole to wear smooth. This causes slipping. Remove the peg, and try putting old fashioned school chalk on the parts of the peg that are shiny. This will create some traction. If the peg still keeps slipping, it may not fit properly and will need to be replaced. If a peg is too tight, try rubbing it with a bit of dry bar soap. Lava brand soap will work quite well. Even a child’s crayon (use black if the pegs are ebony) will work reasonably well.

Bear in mind humidity has a significant impact on pegs. They will tend to slip in the winter and get stuck in the summer. If the problem is chronic, take the violin to a repair shop and check with an expert. The problem might be just a seasonal headache that needs to be dealt with alternately depending on the time of the year.