Savage Model 6J-DL 22 semi-auto

Need help please!!! Have my Fathers old savage 6J-DL 22 semi auto, it is suppose to fire in semi-auto mode when bolt is left out, and can be used as single shot if bolt is pressed in and you manually eject shells. Mine works as a single shot, but in semi-auto it just clicks and doesn't fire. Firing pin mark looks very faint. Sometimes it will fire and will fire 2 or 3 shells very fast in a row by just pulling the trigger once. I cleaned gun very well and it worked correctly for about 5 shots, then back to the same deal. Any help would be greatly appreciated.:o