[gigatron]

Paul Setzer is the go-to guy for Gretsch pickguards.

You can get an old HiLotron pretty easily on eBay or from http://blackriderguitars.com/.

At Stewart MacDonald you can find new replacement tuners that will just drop in without any drilling or routing if you have the 3x3 headstock. If you have the 4x2 headstock, somebody here will chime in to advise.

The old HiLos are pretty weak, especially on a single-pickup Corvette. You could put in a new one with a little bit of routing.

Or, you could send the old one to TV Jones for a rewind. I asked him about it once and he said he would do it, although I ended up not taking him up on the offer.

Or, you could do what Rory Gallagher did and put in a P-90: