Hi there
We had several leaks in both slides. This is want I did to fix them.
1 Check the screws on the side wall, as they might be put in on an angle and water runs in.
Fixed by taking screw out redrilling hole straight refitting a s/s screw and with sealant around it as well. I have replaced all the screws in this way throughout the whole rig. Your'll be amazed how many are put in on angles and some not even there.
2 Check all sealant.
I have resealed most of our rig now. It is an on going thing with all the movement.
3 Check the sealant tape on the outside edge at the back of the fascia, I think this is eternabond not sure. Ours had rusty screws, some how water got in.
Took this tape off, took out the screws and replaced with s/s with sealant, then layed 100mm eternabond on and up the back of the fascia sealing it all up.
4 Also check the that the windows are'nt leaking. I have'nt done ours yet, but will do in the future.
Hope that helps, sorry to bore you, but it is a process of elimination and it takes time.
Cheers Paul