New NiMh pacs sometimes need 'conditioning' since thay may heve been sitting for a while with no use before you bought it. Even if its pretty fresh, the usuable capacity of the pack will increase until its had 8-10, maybe 12 charges. They usually start off having less capacity than a pac will after those 1st dozen or so charges.

A wall type plugin charger is ineffective compared to a peak style NiMh charger that will detect the peak assoicated with NiMh cells being full. When the packs are performaing lik ethey should, they don't need discharging every time they are charged. I discharged mine avery 5 or 6 charges at low rate to try to equalize cell voltages. I also charged my rcvr packs at 0.5amp and never more than 1amp - these small 2/3a cells aren't made to take the heat that charging at 1C type charge rates cause.

As far as a good charger, here's a cheap charger with a good rep, has a lot of features, has a builtin balancer for lipos and will take care of NiMh as well -

http://www.hobbypartz.com/thac6smbachw.html

Get a good charger and cycle your pack - you should see performance get better in terms of discharged mah. If it doesn't, then the pack really was beat.