96 Town & Country alarm problem

I'm having a problem with the factory alarm on my 96 Town & Country. The alarm goes off by itself often, but not always, when I lock the van, either with the lock inside, or with the remote. I've messed with it several times over several years and I've gotten the problem to go away somehow, but it always resurfaces. I can never pin-point how I've fixed it in the past (combination of key in the ignition with locking/unlocking the driver door from the outside with another key has sometimes worked.) I can never seem to replicate the problem when bringing it in for service. Can anyone shed light on this: how to 'officially' re-set the alarm, disconnect the alarm or replace a part/service this thing?