If the jewel is damaged, it will need to be replaced. As far as I know, the pallet jewels on the A7750 are the same as the ETA version, so you can replace them (jewels cannot generally be repaired). Try julesborel.com or cousinsuk.com. Be sure, however, that you do not oil the pallet pivots - these should be left (clean &) dry.
Remove the top plate that contains the redirection wheels & see if the movement runs. If it runs, then the graphite powder treatment should remedy the problem. But if it still does not run, then the problem lies elsewhere in the movement & will likely require a full service.