Old: (8EO 927 189)

New: (7H0 927 189)

Didn't want to install the new one as I'd read it was a one-time-only affair, so I just swapped the plug over. This didn't seem to work make any difference. So after some umming and arring, I went for it and installed it, still made no difference, still have to hold the starter to start.
Have I got the wrong part, or am I doing something wrong?