With apologies to Cliff for following on from his question:-
I believe you can discount any association with the bonnet contact. If the wipers work, then this is serviceable.
If it were mine, I would first be checking you are getting a good 12 v supply to the pump and an adequate earth. If you are, suspect the aftermarket pump, but I haven’t had any frequent issues with these.
If you aren’t getting 12 v to the pump, you will need to check wiring back to the stalk - which could also be the culprit.
Please let us know how you get on Martin.
Regards,
Gareth.
p.s. Afterthought :- you are talking windscreen washers here, rather than headlight washers- ?