Sounds like a pre-1930 issue. Not many people have the 1900 to 1940 stuff and unless you get lucky on ebay only the dealers (and I presume the ME clubs) tend to have the earlier issues/volumes

I skimmed out the old knackered one on my Drummond M and cut a new nut in aluminium which I slotted into the skimmed out clasp mechanism

I burned through two original LS nuts in about a year using my M series lathe regularly, they are very soft to protect the leadscrew so you will need to develop a reliable replacement system

I got a spare lead screw nut clasp lever from ebay so now I can rotate my LS nuts as they fail

Well I had a wee read of the last ME metalling article for myself and it looks like babbit etc could be a lost artform well worth preserving

Metallurgy is almost a form of alchemy and some of these low temperature mixtures seem to have a very high resistance to wear and were used extensively in locomotives

The downside appears to be the price of the tin rich base metal which was very expensive even in the 1980s

Well worth a read:

Usually the thing you have to check is that the lead screw has the same thread thickness all along its length or the nut is going to seize somewhere. I have done this job once on a mill cross slide screw. The original nut was bronze and I degreased it, tinned it , brushed Bakers Fluid on the tinned surface , heated the nut on its degreased screw to run the metal in and kept the screw working a little until the metal set hard to avoid the screw bonding to the nut. It was a very good result and was still good for the two more years that I owned it. I did keep it well oiled though! Colin

Hi Ken, while I was scanning I see Ady 1 has posted the two pages, but I've put them on a single sheet that you might like to save or print out onto an A4.

Regards Nick.