Don't know if you ever got this sorted, but check the drain holes. Partly open the roof so the back is up and so is the cover. Under the mounts are holes that get clogged.
Get a piece of copper brake pipe about 30cm long. Bend one end about 40 degrees. Get a piece of strimmer line or thick fishing line, tie a knot at one and and melt it solid. Feed the thin end up the pipe till it comes out the other end.
Now put the bent end of the pipe under the roof mounting and fish around, turning the pipe 90 degrees as you do so. Keep trying as evetually you will find it will turn and lock. That's the drain hole.
Feed the strimmer line back and forth down the hole and it will clear it out. Finally pour some clean water into the area to fluch it clea.
Simply repeat on the other side.
Regards.
John.
