At one particular account with 5900 phones I've had several hookswitches fail. The small tab on the white rocker with a spring breaks off. The spring can usually be found adhered to the magnet of the speaker (fortunately). I repaired the first one by removing a hookswitch by unsoldering from a dead 5800 and soldering it into the 5900. As expected, relatively time consuming and something that is best done back at the shop.

I then noticed the Platinum series phones have the same kind of hookswitch. Fortunately we've got several Platinums in stock, and there's very little demand for them. I found that the top half of the hookswitch can be dissambled. The white rocker part can then be installed in the defective phone. I've done this at the customer site probably 6 or 7 times. If I know of the failure I'll bring the hookswitch part from the shop. Unfortunately it means sacrificing a good Platinum phone - so far I haven't been able to find a source for replacement hookswitches or hookswitch parts. Fortunately it can be done on site with a small flat blade screwdriver and small needlenose pliers, and in my case an extra pair of glasses to see the small tab. That's what can be a bit tricky, hooking the spring back onto the small tab. Viewing is key - back at the shop we have one of those big magnifying lamps, last time I was able to put the spring back on in less than 10 seconds. But there, ironically - the spring slipped from the pliers and shot across the bench. Amazingly, I found the spring. Due to that I'd recommend saving springs from the old or donor hookswitch.

These phones are in a school, so I highly doubt it's due to rough treatment. I agree with the theory of someone in the shop - over time maybe there's a 'sawing' action of the spring's loop on the white tab? Too bad they changed the design, V3 and V2 phones are totally different and there probably haven't been failures due to the same reason. We're thinking maybe there was a weak run of these hookswitches as it doesn't seem to be common elsewhere.