I changed the oil in my similar WM 250 some tim ago. Like yours the manual says to use Mobilgear 627 but this is no longer available so I got some "gear oil" from Halfords reasoning that if it says it′s for gears and it′s going in a gear box, then it will most likely work. The oil in question is "EP 80W90 GL-4" this is marginally less viscous than the recommended oil but should still do the job, especially with the light use my lathe gets.
Might be something in my Maintenance page that is of interest.
John
Edited By Journeyman on 19/07/2022 13:36:34