Well a new chain might help. If the bushings are damaged (als it rot of looks like it if you look at the pin that is almost out of the tooth there) it can be stuck. And don't use WD40 but use a good chain lube. In this case, get a new chain and see if it fixes the problem. It's only a few pounds and you can probably get it fixed with that.
Well a new chain might help. If the bushings are damaged (als it rot of looks like it if you look at the pin that is almost out of the tooth there) it can be stuck. And don't use WD40 but use a good chain lube. In this case, get a new chain and see if it fixes the problem. It's only a few pounds and you can probably get it fixed with that.