My ABC jigsaw

Can anyone explain this bearing attached to rear of my flywheel,can find no reference anywhere,is it  factory upgrade?,my jigsaw continues

Dunno how to put this to you Dell...your clutch-release system is entirely bogus! 
Its style is borrowed from, for instance, a post-war Douglas (although some prewar Duggies used it too).
However, the rest of these clutch systems were totally different to the Sopwith, and couldn't realistically be applied.
My advice...ditch your system pronto, and in total!
The Sopwith clutch and its release system are far simpler, and that includes better. 

Thanks Paul the reply I was hoping for as I had already decided,although I will have to use a different crankcase as this has been altered as well
It must have been run as this came from the only nearly complete engine I had
Merry Christmas to everyone Dell

if it works leave it alone, it is part of its history, someone may not have been able to get the correct one so used a douglas ?