I have the same problem, but I assume it's from years of the stand banging up against the detent when pushed off it.
For several years I've developed a technique which is the reverse of putting the bike ON the stand, that is to wedge my booted foot behind the thing and control it's return.
I'm not aware that mine flops around behind me as I'm going over potholes! It may do...
The problem with all the Ariel rear stands is that the spring being one-sided excessively loads the pivot on the spring side, leading to an oval hole, which then means that the stand twists one way on return and wears the detent.
Last time I renewed the pivot holes in the stand I had a bit of extra weld gobbed on the stand detent, so it more easily catches the worn frame abutment.
An amusing story... or not?
One night about 27 years ago (!) I was just leaving the Selly Oak branch meeting at 11:30pm, along with several other members. I started the old banger, leapt aboard, pushed it off it's stand, and disappeared into the night...
As I pushed it off it's stand there was a 'tink' on the back of my helmet. I heard it and felt it. I thought it was a twig off one of the trees I was parked beneath.
When I got home I found out what it was... it was the detent from the rear stand. Snapped off! The stand was buried in the tip of the now crumpled back mudguard. Nice!
(AOMCC Exec Committee & Selly Oak branch rep)
'47VB, '51KH, '58FH, '05 BMW oilhead boxer.