Hi David,there is a carb on ebay 330906765165 but it will increase in price
as it is with the correct fuel pipe.The mag dyno arrangement does in fact
attach with a strap,the MO1 magneto has four dowels underneath which locate in four logditudinal hemispherical slots in the mag platform.these afford some
forward / backwards movement and should ideally be undamaged from fretting
caused by a previously loose magneto.slight up and down adjustment is provided
with very thin steel shims the size of the mag base,to give a bit of clearance in the mesh of the driving pinnion,which if is to closely meshed will create a whirring noise.re-conditioned mags are available through various outlets and on ebay,they are expensive.Its prolly worth spending money on a guaranteed unit
than taking a chance on one with unknown history,as the root of most trouble on
the M20 stems from here.A new carb will set you back £225.00,again how much for piece of mind.
hope this helps
cheers Rick