1. Tighten the end cap, there is an internal thread on the cap that sometimes works loose.
2. Tighten the spring on the drop in
watch my vid for how to:http://www.youtube.com/watch?v=zJpQAvum0bM
DIY thanks for your help. Very nice vid. I couldn't see the two tiny mentioned holes to wind the tailcap piece up on mine. However, I took mine fully apart and put it back together and it stopped doing it. I did notice the battery is able to rock ever so slightly up and down the main chamber which can switch through the modes sometimes. Perhaps I might pack it out. Interestingly, this is my 502-b that is causing problems. My two older 501-b's are rock solid. I think they all have the same XML LED mind, or very similar, but the beam pattern on the 502 is ever so slightly different as I think the diffuser might be different.
I never did get round to trying one of those orange peel reflectors to assist in limiting the center spot and allowing more flood. I might do this at some point, but with two 501s on the bars and one 502 on the helmet, they merge nicely into a good overall coverage.
As for the laptop batteries I posted up earlier in the thread, I will post back what packs they are from in a bit.
You can pick up 501's/502's
from british sellers for a tenner or more. Better batteries
can be had too, as well as chargers
for only 5 to 10 quid. Beats me why people order from half way round the world (unless it's significantly cheaper, which in this case it isn't).
I noticed this last year when I bought some. I saved a lot of wait and hassle by purchasing from ebay UK. It was slightly more expensive. At the time I think some people were finding things were taking absolutely ages though from China. Perhaps I left it too late and it was near to the Chinese New Year thing...can't remember.
I just checked DealXtreme and they have a 501-b with XML-T6 emitter for $12.20. That's about £7.60. If you buy 3 or more, that goes down to $10.76 each, which is £6.70. Shipping is free and actually at the moment that item states only 7-10 day delivery. UK ebay - as you linked yourself - is about £14 for a reputable seller at the moment.
EDIT: Just checked ebay and there seems to be a Uk seller of the 501-b for £10 incl P&P.