1" forks
 

I'm in the process of restoring a '91 Merlin. It has a 1" tube- is anyone making new forks with the 1" measurement? I have an old RockShox Mag 21 on it right now, should I just stick with that? Thanks.

Marzocchi makes a few still with 1" steerers, though I think they are only a couple low end models. At least they used to. Not sure if they still offer that.

Clean up and refurbish your Mag-21 as best you can! If you scrounge around enough, you can still find some seals and whatnot if you need.

Otherwise, look on e-bay for a 1" fork in good shape.

Both Suntour and RST were still making 1" threaded forks as of a two years ago. All low end, entry level stuff. You'd be better off with your MAG 21.
If you go the ebay route, be careful. There were a lot of elastomer forks from that era that are now useless because the elastomers have broken down and replacements are almost impossible to find.