JCB 530

My father has a 530 and it died the either day and wouldn't start and they jumped it on the starter and got it started and then it would only go in reverse. Now it will start with key but will not still go in forward but works in reverse. We don't have a fuse relay diagram or a wiring diagram so hardly know where to head in at. Relays do click when shifting into forwards but can't tell which one or ones.

Any help would be much appreciated.

JCB 530