The connection problem you describe is pretty common, since those adapters get yanked everytime someone trips over the cord.
I haven't been inside a Super Filter, but here's the standard procedure for fixing one [I'm going to assume you have already eliminated the cord as the problem.]:
You need to unplug the unit and disassemble it to expose the printed circuit board. Chances are the adapter is housed in a plastic box, which is in turn mounted to the circuit board with a couple of pins (2-4) on the bottom. Check to see if the housing wiggles or if you can see any loose solder joints at the pins. If you can, you'll need to resolder those pins. Mark the pins with a felt pen, Position the circuit board so the adapter is on the bottom and the weight of the circut board is on the adapter (use a couple of books) [The weight will help seat the adapter during the next step.]. Apply some rosin/flux, then touch the hot solder iron to each pin, one at a time. Each should reseal. If necessary, apply a bit more solder to each pin, but do NOT use any more than absolutely necessary [always use rosin core solder for electronic repairs, never acid core]. Hold the soldering iron on the pin only just long enough to liquify the solder on the pin and the board connection. After cooling, the joint should look shiney [not dull and grey]. The pins should be stable and the housing should not wiggle. The new joints should not join any other connections than the originals did [Too much solder can run and bridge a couple of pins, creating all sorts of problems.]
In the worst case, the housing will be cracked and you'll need to remove it and replace it. Take it with you to a nearby Radio Shack. They probably have the part. Then install it as described. Test the unit, wiggling the adapter carefully to make sure the problem is gone. Reassemble the unit when done.
Estimated total time: 30 minutes. Estimated cost $0.05 [for solder] or $3.55 [if you need a new housing].
Estimated cost if you have a tech do it: $50-$100. Estimated turn around time: 3 weeks and 1 hour [three weeks sitting on the shelf waiting, 30 minutes to repair it and 30 minutes to write the bill up and call you to tell you it's done!].
