Which measurement is actually failing are there actual readings you can report ?

I'd expect a tester checking an  extension lead to be doing 3 distinct tests
1) resistance of copper conductors - should be low, sub ohms
2) resistance of insulation - should be high, megohms  and
3) polarity/ cross-over checks - and that should be 'no crossovers'/

Which test is actually failing may be a clue.

Mike.

Nothing that complex.  A simple Pat test using the power cord button option. (4th button on bottom) 

Older tester: passes.  New tester and both units fail.  Wondered if anyone else had seen this? 

Do the 'Earth continuity'/'Insulation resistance'/'Polarity' lights not indicate which test failed?

   - Andy.

It has to be that complex - what do you imagine it is doing on your behalf? When a part is failed how to you know what fault to repair ?

Here is the manual for that model

Which of the tests in that manual are you running ?

Mike.

It has to be that complex - what do you imagine it is doing on your behalf? When a part is failed how to you know what fault to repair ?

Here is the manual for that model

Which of the tests in that manual are you running ?

Mike.