Im afraid this is not good news.
E52 = No signal from motor tachometric generator
Possible Cause = Motor faulty; wiring faulty; PCB faulty
Its possible that the carbons are jammed, so that the first thing to check.
Then check the wiring into the multiplug on the motor, the wiring can break due to vibration.
Failing that its probably the pcb.
Because there is no definitive test, for the homeowner, to prove if its the PCB or the motor, I would suggest you get a fixed price repair as this would include ALL PARTS needed.
If you'd like a quote, please let me have your postcode
In the meantime,
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