If the wires look good going into the gearbox, you'll be safe fixing/splicing the wiring that is good outside the gb without opening it.
I'd switch over to a t-plug (deans) but if you want to stick to the mini Tamiya plugs...
http://airsoftdepot.ca/catalog/produ...roducts_id=572
http://www.torontoairsoft.com/BOL-Ta...et_p_4795.html
If you have a local rc/hobby shop they should have parts too