I have done this three times (3 different engines) in the last 2 years. First
spray some loosening stuff on it (WD-40 or equiv) Then I take a big steel washer
and grind it as required to fit the slot. Grab the washer with a vise grip
and/or stick a steel rod thru the center of the washer and "as bob is my
witless" loosen it. All three times I have been amazed that it came loose so
easily.

Pawling NY

Cars I have: 93 Eurovan MV
                  75 Westy
                  73 Super

Cars I had: 89 GTi 16v
                 87 Syncro
                 83 Rabbit GTi
                 82 Vanagon Diesel (w 83 GTi engine)