Aqualarm water flow sensor

[PeterBld]

I had one of these fitted on our previous boat. Had a slide adjustment to set sensitivity. Had zero problems with it over 15 years.
Fitted the same type to the current boat and it intermittently does not sense no flow (I.e. Does not alarm on switching the motor to "on") and does not alarm when stopping the engine.
Anyone else had this?
They appear to have ceased this model and the new ones appear to use a paddle wheel system. Anyone using these types?

 

[Ralph Johnstone]

Not familiar with the newer models which use a paddle deflector action, but my older magnetic slide model is still working perfectly.

There doesn't appear to be a sensitivity adjustment on the newer model so is there any chance you may be looking at a lower than normal raw water flow ? Sorry, had to ask ?

 

[PeterBld]

At this stage still trying to work out why the old one is failing occasionally. If I tap it the unit works so ????
As regards the new units I will contact the US suppliers and make some enquiries.