Is the junction between the lead of the lamp and the lead of the battery a bit loose? Mine is far from being a tight fit and as such rattles undone when riding bouncy stuff.

Like a glove here. No problems.

Mine's a very snug fit (ooh eer missus)

Tight as hell and requires a hell of a force to separate them.

Mine is very tight. It sort of 'clicks' into place. Are you pushing yours together tightly enough?

+1 tight as a gnat's….

Mmm, my theory is that it is perhaps too tight so that I can't get the male part inside the female. It connects enough to make the light work, but once I get on the rocky stuff it shakes loose.

ho hum, looks like a return. This is why I hate mail order. Glad I bought it in the UK tho'

silicone grease on the connector helps 🙂

defo a duffer. The charger connects nice and snug, but the outer diameter of the battery female part and the light male part are the same, so no way the sleeve is going over 🙁

you might be able to match it with a new connector from Maplins, 'tis an easy enough soldering job – would be quicker than returning to China. If not replace both with a matched pair.

Connector on mine was very tight, found I had to twist it slightly to seperate them. Eventually this twisting broke & shorted the wires – so I had to replace both fittings. Much better now…

Both mine are very tight connecting battery to head unit – a bit too tight to separate sometimes with cold hands.
I found some silicone spray helped.

The fit between cells and chargers is a good snug interference fit but noticably slacker, as it doesn't "click" into place in this case.
If your charger to cell connection is tight, chances are that the head to cell would be too tight and consequently not positively engaging.

Hope that helps.

'tis an easy enough soldering job – would be quicker than returning to China.

I bought it in the UK but I'm definitely not getting the soldering kit out for something that should be correct in the first place

ah, not as bad then, I'd get it sent back.

Mine was China and I didn't fancy waiting months just to get the same connector again.

Mine was well tight. I just massaged the female end until she loosened up some.