Corrector plate is now sparkly clean! Followed the instructions in the manual (for a change) and no sweat whatsoever. Was done in about 45 minutes all up. The dust came off quite easily with the compressed air. However, I got a little freaked out when the can of compressed air put a little bit of propellant onto the edge of the plate at one stage. I carefully wiped it off with one of the little tissue pads I made. The isopropyl worked a treat on the layer of residue on the plate itself. After my handywork the corrector plate looked brand new.
Hopefully I haven't wiped the EMC coating right off the plate! I'll find out this weekend when I take the scope out - we may get some nice clear skies on Friday night.
Before (left) and after (right) shots below.