You might actually take the cover off the regulator & look inside to see how rusty it is.
Remove the battery ground strap first so you don't short the innards with the cover.
Running a clean dollar bill through the regulator points can help clean off what's making them sticky, if the points are not too burned/pitted/corroded.
If you file them square, they will be clean & not stick, but the regulator adjustment will be thrown off.
(Before deciding to file regulator points, read the adjustment procedure in the manual. You may decide against it.)