@Dowser That's arcing alright! For what its worth, its usually quicker just to desolder both sides and whip the panels out to get to the bottom.
@Paul Easton I think I would try using a foal roller to lightly coat the stator before placing he nylon mesh back down. The nylon material usually stays on the stator pretty well - but if bits are rising then a little contact adhesive works well to stick it back down. Sometimes if there has been arcing, you can get pinholes etc and I always worried that you'd have carbon build up around them. So I often use a little nail varnish to isolate them a bit. If you have to remove and glue down the whole stator, make sure that you have nothing sticking up that comes close to the mylar. It will arc in use.
By the way, if you have replaced the mylar, its devilishly easy to leave little "hairs" of melted mylar when you make the holes around the centre screw supports. I advocate looking with magnifying glasses with good lighting to make sure nothing is there.