Fingers crossed

My 40D is playing up again. It's a repeat of a problem that saw it being returned to Canon for the first but not the last time during its first year. A bit of googling reveals that it is a known problem. I have three choices: send it to Canon; take it apart or; try a quick fix. I now have the Isopropanol and I'll work backwards from there.

Edit: Just tried Isoprop method and it works.