TIP120 will do the job. You did solder the power (yellow wires from memory) to the banded side of the diode on the coil ?
I have the TIP120 handy if you need one 
will order some tip120 from Greg but may grab one from you in the meantime and bring back when the order comes. BTW is tip120/122 the same and are they ok in place of tip101's.
I connected the two green wires to banded, tested coil and got 10.7ohms just like on the space invaders. Checked banding on the pop bumper and switch I replaced and ok. Can these just give out or does something cause it that I need to address?
Might see you tomorrow mate.
