When you find your instrument tone is change or have noise, there is probably have conditions like degumming, un-tighten fine tuner, chinrest get touch with tailpiece, fingerboard de-glue, or nut groove not deep enough… You need take it to see expert luthier to fix.
1. Top plate, back and side degumming
Violin top plate, back and side would degumming resulting from damp. Repair method: insert with specify thin blades open the gap and move around to check other place open or not, then apply with pig skin gelatin. It need to boil the glue, if it difficult to obtain, polyvinyl is also workable which is easy to get. With this glue the shortage is hard to open next time if need to repair again next time, it may get the wood damage.
Use specific clamp after gluing to tighten the plates and keep it for some time.
1. Sound post falling
Sound post diameter between 5.5~6mm, almost same size as the f hole. So it is difficult to take out. Method: take violin horizontally and make the front toward ground, and hold it high over your head to watch the sound post. Then slowly tilt to one side to make sound post stuck at the f hole then take it out with your hand or tool. Using sound post hook to stick in the side with lower slope, if sound post hook unavailable, you can DIY one by yourself, use 4inch length thick steel wire twisting to S shape and hammering sharpen one end.
Put the sound post in from F hole, upright it at middle body close to bridge right leg which the
distant about 5mm from bridge. Check it from f hole and endpin hole to see if it well upright. The position is very important which effect tone significantly. You need some tool to mount sound post, usually there are 3 tools for fitting it.
Bows need cleaning when it get dirty and greasy. Clean method: use warm water soaking hair (attention! hot water will shorten hair), apply soap and gently rub with hands, afterwards, rinsing2~3times with clear water. Finally use dry cloth to wipe. Be carefully don’t wet bow tip and hair chest during whole procedure.
After long use, hair would get smooth and hard to apply rosin, you’d better change new hair or reverse mounting hair side and use for some time.
5. Bridge repair
bridge should be upright and align at the middle of f hole. Check it regular make it at correct status. Change bridge once the bridge bent. Sometimes we see bridge tilt effect vibrate severe. Due to bridge shape slight lean back thus make it slide forward, and it is not easy to perceive, but sound will be restrain more and more.