If it's stuck in the up position, that sounds like a false-neutral to me; if the down position, it could be that the return spring has gone over centre.
False neutrals can be caused by poor operation of the pedal (a common problem is trying to press the pedal with the instep of your foot and your toe hitting the boxing above the pedal area, preventing it from being pushed all the way down (make sure you use the ball of your foot and that your toes clear the reinforcing), or it can be caused by your gear linkages being out of adjustment - I occasionally get a false neutral on 4th, if I don't pull back on the selector lever a little and really need to adjust the linkages. On the up side, I'm very strong in the legs and can easily reset the pedal, but most other people really struggle with it.
Like others have said, the pedal is a gear change pedal and should never be used as a clutch. If you do, it will rapidly wear out your gearbox, which is both expensive and difficult to repair. If you haven't already, get yourself a copy of the driver's handbook at the very least and read it thoroughly. One of the most critical things is the "pedal down" procedure, which involves selecting each gear (with the engine not running) and giving the pedal 6-10 full strokes, before selecting the next gear; this ensures that the automatic adjusters are kept tight (you can't over adjust them, so sometimes if you have a slipping gear, a large number of pumps will get it back in spec, unless it's too far gone).
Also make sure that you use the correct grades of oil, particularly in the gearbox:
http://hmvf.co.uk/forumvb/showthread.php?13284-Saracen-RR-B80-Fluids&p=399965#post399965
Cheers,
Terry