So, after a few more weeks of constant play it seems the G and B strings do slip ever so slightly out of tune.
I'll take a closer look at the nut & will also re-string the guitar, even though I think it's strung fine at the moment. Blaming the tuners is the last thing I'll do but, even aesthetically, they're starting to grate on me, particularly after studying the tuners on the new M20 (which are actually 20:1, not 18:1 as I'd first thought). I'm really falling for the look of the ivory buttons & feel they suit these models better than the slight bling of the chrome/nickel tuners...
M120...
M20...
So, I did some more digging & have found that Grovers only come in chrome. Schaller, Gotoh & Waverly all do ivory-buttoned tuners but are pretty expensive. Then today I discovered the Kluson Prestige line & see they do a set at a more affordable price (half that of the Waverlys). I've only limited experience with modern Klusons but the "single line" ones a have on another of my guitars are great. Hopefully these work well too...
I'm hoping there won't be a problem with spacing on the headstock. The stock mounting plates are a tight fit & a slightly different shape, plus, these Klusons are a slightly different shape.
You think you can't, you wish you could, I know you can, I wish you would. Slip inside this house as you pass by.