I ended up drilling a small hole on the lowest point on the lowest side when in its side stand. That side no longer holds all the water. Just did a very wet week in Wales where the bike spent a lot of time on the centrestand and the other side held water so have drilled a small hole on that side too. The holes are just in front of the big rubber pads that sit in the frame. It’s the lowest point when fitted on the bike. May get the cover removed, retaped and refitted if the extra hole does not do a good enough job.
