Guess I have to do all this...

If it does not help, would you recommend to replace thermal fuze? Should fuse replacment lead to reduced ball heating?

Still got a blockage somewhere that is restricting the airflow? But must be fairly minor if it runs for 15 mins before shutting down.

Where blockage can be? Canister is clean, all hoses are clean... But the ball gets hot fairly quickly. Where can I check?

I cleaned the commutator.
On reflection, the bushes are a bit worn, but the springs are good, so I would expect maybe a bit of noise, but not total failure.

I will need to get a multimeter on the triac, just in case it has failed and not blown a pin

Cheers for the reply.
I stripped the motor down and the brushes and springs seem to be in fairly good condition.
I also checked the triac, and the legs and solder are intact.
Then, strangely, when I put it back together again, it wouldn’t start (light on power control flashes on but nothing more).
I then tried swapping the motor from my working C3 (403-42/2) and it started up fine.
Considering the component parts of the 408-42/2 seem ok, and neither the bushes nor the triac seem to be the problem - which seem to be the most common reasons for motor failure, I can’t see what the issue could be (with the motor).
Think I’ll have to wait till a scrap C3 appears.

i recently picked up a 'dead' C3 for a few quid as it had all the tools and thought, at the very least, the spares were worth the investment.
i took it apart, and sure enough, the motor etc was filthy. After a partial disassembly and good clean, i got it started, but with a strong burning smell.
To cut a long story short, i have come to the conclusion that the best action is to replace the motor.
The existing one is 408-42/2.
I have read a few posts about compatibility of non genuine motors, and wondered if other miele motors would work, as i cant seem to find a 408-42/2 at the moment.
Is there a list somewhere of motors which I could use ?


thx