Although I have two MagChargers of different age, I don't see any difference. I know, the lamps have been upgraded from 8,4W to about 10W, but they are surely interchangeable. How this would work out with chargers I don't know....
I would test the battery first, before throwing money at it. Buying a lamp doesn't break the bank, but a battery and a charger may become nearly as expensive as a good secondhand set!
Do you have a regulated power supply with current limiter? I yes, turn the voltage to at least 9V, and the current to about 0.3 amp.
Connect the battery for at least an hour, and after that let it rest for a few minutes. Measure voltage now, it should be over 6 Volts at least. When not, the battery is no good anymore!
Timmo.