Monobloc tap one of the lever handles working loose

[wobblymike]

I have just had cause to change the hot ceramic valve (VR04 Type) IN my kitchen tap because it was dripping. The replacement valve has cured the drip but the M4 securing screw that came with it was shorter than the original and did not protrude through enough to engage in the head of the valve. IT also had a fatter head as I found to my cost because it took me ages to wiggle it out of the lever housing. I therefore used the original screw which was fine initially but worked loose within an hour or so. I have tightened it repeatedly but it just works loose. I have been back to the seller who can't help. Am I missing something? Any ideas would be welcome.

 

[snowhead]

Is the old screw too long and bottoming in the thread in the valve?

 

[townfanjon]

As above , if not you could try a bit of loctite

 

[Welder]

Post some pictures and I'll help if I can.

 

[wobblymike]

Thank you for responding. Two days ago I tried a M4 16mm screw in the handle that is longer than the original (12mm) and much longer than the one supplied with the valve (8mm). It seems to have resolved the problem as the handle has not worked loose so far and before was doing so within a couple of uses of the tap. I find this very odd - when I put the original valve back in with the original screw it did not work loose, With new valve in and original screw it worked loose, now with new valve and longer screw it seems fine. The old and new valve are identical - don't get it. Thank you and all who responded