If the card jams right after it gets fed in (and usually makes a horrible screeching noise) then your card idler roller is missing. If the user can find the little plastic roller rolling around and they want to try it, it is pretty easy to put back. If it is missing or they aren't capable REPLACE PRINTER. If you want to try to fix it over the phone, have the user unplug the printer and take out the cassettes to cool it down more quickly. Give me a call at extension 2104 and I will come down and show you how to do it, no tools required.
If the card jams above the film but you are sure the card idler roller isn't missing, it isn't actually a jam. The film has probably been melted or torn. Follow that link to see what to do.
If the card jams in the flipper on its way to the laminator, it may or may not be a hardware fault. Almost always, the machines I get back for this are NTF; the users did not push the printer/flipper and the laminator together well. Thumbscrews help but are not really necessary. As long as the two halves are pushed together the card will transport just fine. To test if this is the case with a site that does not have thumbscrews, have them open the top of the flipper. After the card is flipped and the second side has been printed, the card will move to the laminator. When the card enters the flipper, have the user wiggle the laminator against the printer. It will usually work and you will know that the problem isn't with the hardware, the site just needs thumbscrews. SHIP THUMBSCREWS
If the card jams going into the flipper and you are sure, really sure that it isn't the problem above, then REPLACE PRINTER. But only if you are really, really sure.