A slightly alternative approach is to get two gears which DO give you the
ratio you want and mount them outboard of existing change gears of
smaller diameter (turn a two-size mandrel, mount, drill & tap three
holes, then bore the new gears large enough to take the axle-fixing
screws). You may have to do some playing about to find a combination that
fits your existing gears and carrier travel.
It beats looking for that ratio in your particular pitch. For Minilathes
in particular, Sherline makes an affordable 127/100 combination.
It's not a good sign when a manufacturer doesn't provide replacement parts.
I wouldn't take one person's opinion as the final word, though.
Then again, it may take some creativity to get someone to go against that
scary, threatening, carved-in-stone company policy, and make an exception.
Something like a letter to the company CEO, spelling out in graphic detail
how your neighbor's dog ate the grear and you've been looking thru steaming
hot piles of stool trying to reclaim the gear, to no avail.. but then again,
s/he might be a cat lover and feel no sympathy at all.
The RC/model industry is fairly vast in terms of accessories and "upgrade"
parts, making a wide variety of small mechanical parts much more commonly
Trouble is, generally, RC and various parts suppliers do such a poor job at
listing actual parts specs, finding something can result in a fairly
complicated research project.