Boiler pump keeps failing

Hi, looking for some help with my boilermate 2000. Its been working fine since we moved into the house about 4 years ago. No sludging and nothing of concern. However recently we've had some issues with the boiler pump.

There was no central heating and the thermal store was getting cold. However the LED light for the boiler pump was on along with the central heating pump. The central heating pump was boiling hot but the entry and exit pipes were warm but not as hot as the pump, but the pump was not spinning, I hoped the silver screw on the front of the pump and could move with a screwdriver and seemed free to move.

As I needed heating I moved the pump header from our DHW pump to the central heating pump. The pump fired up and we now have central heating after the storage temperature was too up speed. Anyway I bought a new 15-50X18 modulating pump and fitted it onto the DHW, which is now giving us hot water from the taps.

This morning however the same thing happened again, the boiler pump is not spinning and the pump is boiling hot, we have no central heating, but I do have DHW. I can't believe that a second boiler pump has now failed, even although its not the new one. Can this be an issue with the ACB/Control Unit? Has the pumps been damaged at £140 a pot I need to make sure I'm not buying a new pump again for it to be damaged. Looking for advice.

Just for info, all three pumps on my boilermate 2000 are the modulating type, I have no senor errors and did replaced all 3 sensors 2 years ago. DHW is working fine and dandy.

Try this.
Remove cable from pump. Switch off and make safe first.

Piece of 3 core flex with 13 amp plug top.
Connect to pump. Plug in extension lead and test that way.

Or test with meter if one available.

Mike

Managed to fix the issue. It was related to the ACB, after switching off the boilermate for a few hours, switching it back on seemed to have made it work again, pump and all.

So I removed the ACB and replaced all the electrolytic capacitors with higher performance, higher temperature types and now the system has been fine for more than a week.

Its also more stable in that the target temperature doesn't change every few hours. It seems to have locked onto a 65 - 70 temperature range which my boiler can meet without issue.