Have you contacted Petar K? That would be your best bet and the first thing to do, as he may have some top caps from the V1 run. An alternative is to find something of the same inside diameter like a socket etc, then use a little pressure and round the cap up again. For the switch, it is actually pretty easy to rebuild.
Use a soft clamp to hold the top (I just use a C-clamp and two pieces of wood).
Use a small engraving cutter dremel bit to remove the glue. Since you are not replacing, you can probably leave most of the glue in, just clean it up.
Then use JBweld to fill it back in.
If all fails, you could send to Petar K or myself.