Hello,
I'm not sure about the installation shown; is the square insert surrounding the switch wood?. It seems to be neither the original intention of a u.s. fruit machine button (which was fitted to the early production) or the fall-back of a metal insert holding a small cylindrical switch, without illumination.
The picture from M4carp is how early ones usually went once the illuminated button broke. Deith Leisure handed out washers and switches like that. TBF, the switch is as used on later production, but the washer isn't. The factory changed to a metal insert holding the switch, at the right height, while the washer leaves the switch in a recess, which fills/filled up with ash and detritus. At least this washer was painted, which I have to admit I didn't bother with.