As Julian says and illustrates. The different types and part numbers are shown in the Lucas parts lists, and versions were fitted to K2Fs per the specific application as set out in Lucas' Equipment Specification by machine.
It's the cylinder side one that's the pain with a manual mag on As, as it really does need the crank. Uncranked 45° angled handed ones simply will not go on that side.
If a pick-up is too loosely retained by the clip, there's a risk of brush damage and / or of water ingress, but they'll all rotate a little bit if pulled and pushed. Shouldn't really 'rock' though. (This excludes the 2 screw ones used on late K2Fs and on Comp versions.)
If there's a genuine concern, I'd check the gasket is present and of a proper thickness, and that the clip is undamaged with intact blades and that the pillar is screwed fully home. I've never been averse to a smear of Wellseal or equivalent myself, to help with sealing and with staying put.