Grant oil combi - pumps intermittent

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Hi,
My external Grant Combi vortex 26 oil boiler, possibly the world's most unreliable boiler, had another wobble couple days ago, no hot tap water, as the HW pump was silent, so gave it a tap on the speed selector dial and it whirred into life briefly. Took it apart, fiddled with metal wiper contact behind red dial and all good again......

I've had this happen previously on the CH pump last year, it seems the speed selector dial on these pumps falls to bits inside (plastic red dial that holds a metal contact wiper in place) and a bit of bodgery gets it working. Anyhoo, I wondered if it's possible to buy just the plastic electronic box that attaches to the pumps? (the red knob in pic below is what breaks)
Grant-Circulating-Pump-MPCBS43-150x150.jpg

I'd like to fix the bodge if possible but don't want to replace 2 pumps that work fine, other than for the lousy plastic dial that fails.

I'm an electronics engineer (but no plumber or boiler expert!) so am happy to do certain repairs on this troublesome beast.
 
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It is not possible to replace the electrical housing on the pump. The early wilo pumps have a piece of copper strip across the speed switch which seems to harden an bend away from the contact. Newer wilos are ok or any cheap pump that takes your fancy. Put a plastic bag over the electrical box on your new pump (dhw) as sooner so later a leak from the plate hex will drip into it.
 
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Joined
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Thanks for the reply, good info to know.

Yes the copper strip is what I bent slightly, a small piece of plastic fell out which I assume held it in place and broke away. One pump was replaced in 2014 (under warranty) but that switch failed in 2017... so pretty poor I reckon. Oh well, the whole boiler has been the most unreliable boiler I've ever owned so never really surprised when it fails each year! it is nearly 9 years now.

I think it's had 3 power switches (all seized), 1 heating pump, 2 flow switches which spray high pressure water mist all over the insides, 2 expansion vessels and probably other things I can't remember
 
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