I have been going through a few jetdirect cards recently and generally buy them over the internet 2nd hand. The other day I got a box full of 610n and 615n broken ones for a tenner on Ebay and managed to revive a few of them with a heat gun and a bit of luck

The activity light didn't show up but the card worked fine, the first tiem I did it I swapped the working card for one that I had just tried the heat gun thing on and the printer died and wouldn't wake up... i thought I had fried something but it came back to life after I lugged it down to my office

Love a bargain