The bosses screw into the seatstays, not welded. The screw-in models corroded and broke. The problem is that Merlin used bosses that have a 1.5mm thread pitch vs the normal 1.25mm.
I have contacted the newest owner of the Merlin name, Competitive Cyclist, and they are working on locating a part. Any suggestions?
'''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
American Bicycle Group bought Litespeed and Merlin (among others) several years ago and sold both brands for quite a while. I believe Merlins were made in the Litespeed plant in Chattanooga, TN for most of that time. I'd try contacting ABG, or more specifically Litespeed, to ask about getting those parts. Litespeed's Blue Ridge and Appalachian models used cantilever brakes and may have used the same mounts.