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Is the sound of a pressed note continuous?
Do any of the keys 'sag' down into their places?
I suspect that, if there is not actually a stuck keyswitch for one of the notes, there may be some electronic or electric problems in the works.
To properly diagnose it, though, we need to know whether it is an 'original' B3 Hammond, or a later make with a different internal composition. The original Hammond had a tonewheel tone generator, the recent ones are of course less bulky and purely electronic, pretty much.
Can it still play notes?
What exactly is wrong with the pedals?
And, where are you located? obviously you will most likely need a recommendation to a local organ repair specialist.