Webasto dosing pump

[nickfryer]

Hi all any thoughts on a webasto pump working intermittently. 
 

No tick tick on start up but if I tap the pump gently it will start and run for ever but once it’s stopped it won’t start on its own 

 

almost like it’s sticking inside, don’t think these are repairable though.

 

any thoughts appreciated. It’s a webasto thermo pro 90 

 

thanks all 

 

 

[MtB]

I suspect a poor electrical connection, probably on the plug.