I bought some psp #555 white ones to try in AFM.

Couple of questions -

The ones that actually worked were good, but there were two duds out of six, so I was wondering if they are prone to manufacturing issues? I'll take those four out as the area needs six, but they were quite effective. However, if they have a high fail rate/defect rate, I'm concerned.

Secondly, do people find they tend to slip out of the sockets? I've had one just sort of slip up and out of contact, never had that happen with normal lamps.