Wallysue, I don't believe the 1500 and the 1510 have the same setup. I have removed the adjustment assembly, and it looks like it is simply a threaded adjuster screw that goes thru a bushing that is both internally and externally threaded. I have sprayed it with WD40 and penetrating oil, didnt help. I have also tried heating the bushing with hopes the thermal expansion would help, Still no luck. Any other ideas would be appreciated.