Does anyone here have written instructions, preferably illustrated, of how to strip and replace the keys on a bass clarinet ?

I would simply take keys off that aren't blocked by other keys. Line them up in order as you take them off and assemble in the reverse order. Make sure pivot screws, etc. go back on in their original locations. You can create dissassembly and assembly order lists as you go if you like.

The order of setting the key regulations is much trickier. I would recommend a good book. Reg Thorpe has a good one.