Hello all -
We had the same situation with a 2004 Vectra (previous coach). I'm attaching a link to a Youtube video the shows what we did to fix the problem.
The basic problem (for us, anyway) was that the plastic triangle slide pieces and worn down so much that they didn't give enough elevation, with one end being worse than the other - and all of the symptoms that everyone describes here.
I ordered the "triangles" from HWH who shipped them right out. It's a tedious job and a little dirty (though not as dirty as shock absorbers!) but possible to do. The hardest part is fidgeting with the little triangles to work them in through the small space that is created....but I am here to tell you that it can be done and fixed our problem. If I can do it, then persons of limited ability can!!! The part that I had to figure out was the jack to support the slide - that is essential for the procedure to work as the openings aren't big enough if the ram is bearing the weight of the room.
Just my .02 and good luck should this be the problem. You can look at the little slide triangles without removing anything and pretty much tell if they are worn and have grooves in them. For all that I know, others may have different problems producing the same symptoms. At least this one you can see before tearing things apart so that you know it needs to be done before disassembling just to find that they are ok.