Hi Brad-
I had this on both a MKIII and a MKIV, and unfortunately both times I had to replace the starter. The problem is usually with the solenoid/plunger inside the starter itself, and while that part is cheap gaining access to it is difficult. You could try replacing the starter relay in the fuse box (as I did with my MKIII) in case it is that, but that cost me over £30 fifteen years ago and made no difference.
I sincerely hope that you find an easy solution to the problem, but if that doesn’t work it’s worth paying out for a new or reconditioned starter as it’s not a job you’d want to do twice.
Best of luck,
Regards, Mark.
