You can use lumiweld to do a more permanent repair also....

So, my bike seems to be running very hot and I thought to inspect the impeller if it not maybe spinning freely from the shaft.

Then I noticed.... the damn epoxy I used to build up the corroded areas became soft and started to break loose... also the hammerite was coming off!!

The epoxy is rated -35'C to 150'C - is that not enough? Or could it be the coolant (Motul Motocool Organic) that's causing this?

Man I'm so dejected, I'm going to have to redo the entire job

Possibly. Would it not be less stressful long term to just save up and get the required parts brand new?

Fit a new case! And forget it, Job done for ever. (£100 with seals)

I just discovered damage to my brand new 2021 430 RR-S, but 4 months after taking it home from the dealer. They told me then can't put in a claim after it leaves their store. I haven't even ridden the bike yet and now have to pay for a radiator. Nice. Another dealer in Ontario said they had a bike come in from Italy with a squashed radiator, but replaced it under warranty when it was discovered on the PDI.