Might be the solder they used, or like you say, the coating on the spring doesn't bond well to solder. Might have to actually arc the solder fully over the base ring of the spring.
Hhmm. Hobbyists typically use leaded solder, while manufacturing uses non-lead solder. I'd think leaded solder should work fine with silver, not sure bout non-lead. Always wondered if silver coated springs is real silver, or do they cheap out on the thickness of the coating so much, the bonding is a problem.
Do you mean the XHP35 HI version? i dont know, Haikelite only mentioned briefly yeah could be that one. but frankly i have no idea but that one is a zoomy right so that could not be it?
yeah Pete7874 also has the same spring problem, i notified Haikelite earlier and they are aware of the problem.
I opened the board from MT02 and MT01, i noticed that the solders are not flowed properly and the solder was rather dull no wonder you could crack the solder easily. i had to reflow that and replace the solder with a usual leaded solder plus a little flux and it was also only soldered on one side. I wish they could improved that, kind of ruined an otherwise a good quality light.