I did that fix temporarily, but eventually replaced it with a new solenoid. I don't like things to be non-functioning if I can help it.Ended up cutting a groove into the solenoid as specified here: http://www.delica.ca/forum/viewtopic.php?f=95&t=17802 and I now have O/D again- just in case anyone runs into a similar issue. If you do this you won't be able to turn the O/D off with the switch.
Also wanted to say that my issue manifested intermittently: E.G. the van had trouble shifting into 4th at around 60km/s and eventually that became harder and harder until I could no longer get into 4th no matter what I tried. I think the mechanical aspect of the solenoid just gave out gradually.
But bypassing the OD solenoid would make the OD button a great switch for an immobilizer function; with a discreet warning light on the dash! Actually, I would bet it could be the switched power source for the IP shutoff solenoid (i.e. a pretty easy 1 wire mod).