Right. "Easy things first" my dad used to say.
It is the rear bearing, so not the one at the driven end, yes? So it is taking a little torque, imparted along the shaft from the driven end, but nowhere near as much as the business end. Here's what I'd do first.
Take the casting off & clean it. You can do this at home and without risk to life, limb or the pursuit of happiness by washing the worst off with repeated brushings with paraffin, then petrol to finish off. Now get a teacup full of ordinary washing machine gloop dissolved in boiling water - use as hot as possible, repeat if in any doubt. Dry with a hair drier or in a low oven.
The aim is to get the broken ends and the surrounding area completely grease, dirt & paint free, so you may need to scrape the paint off at some point in the proceedings.
Using hard set Araldite, (takes 24 hours to set) apply to the broken ends and wire or gaffer tape the casting as required to join the ends and hold the whole thing steady.
Using one of the better plastic metals - Loy or David's are pretty good - apply a layer to the inside of the casting, covering the cracks and set into the first layer a previously prepared length or two of steel rod, bent to take the shape of the casting & of course covering the fractures. Encapsulate with a further layer of plastic metal & wrap with tape if required to keep it in place. If it was me, I'd do one at a time and treat the unbroken one to the same treatment.
I reckon this should do it. It is cheap, invisible, does not distort the casting, you can do it all yourself and - most importantly - is entirely reversible if it turns out I am wrong and it fails in service!
"Easy stuff first"
Regards,
Kim Siddorn.