Buzzing sound coming from the circuit board as well as the pump

Buzzing sound starts when DHW is turned on. The buzzing is also coming from the pump.
--> Changing the pump did not make a difference.
--> An electronic engineer tells me the "electronic filter" on the circuit board may be on its last legs
and this would make the water pump judder.
--> LED occasionally indicates "T2" sensor is faulty
--> The boiler is used only occasionally
--> Hot water is coming at the taps
--> When the buzzing on the circuit board reduces the water pump starts to judder
--> The judder stops when I switch the mains off and then on again

If the circuit board was the source of the problem where would I get another one from?
How much would it cost?

Your help is very much appreciated.

Last week I spent £600 getting my Pulsa Coil 2000 drained and descaled in order to fix the knocking sound it was making over night. The knocking sound is now fixed but I now have a new sound! Every time I run the hot tap I get plenty of hot water but when I turn the tap off the pump starts buzzing. The buzzing stops about 4 minutes after turning tap off.

I would be grateful for any tips to stop this.

Thanks

Ed

I switched the pump speed from "3" to "2". This seems to stop the buzzing from the pump.
My electronic engineer friend measured the voltage going to the pump during the buzzing.
He found that the voltage of 131 v ac was unsufficient to turn the pump when pump speed
setting was at "3"; Consequently, the pump was juddering/buzzing and getting hot.

I intend to replace the boiler if any more issues arise as the technology it is using has now been
superceded. It is becoming expensive to keep repairing it and replacing parts.

Hope this helps.
praxyp

Sorry to drag up an old post, the pump in the pulsa coil 2000 is designed to run at low voltage when the psc controller modulates its speed down, it is therefore a special pump and needs to be replaced with the same one, a standard 15-50 pump will not work properly