Thanks heaps guys.

Just a quick question. The reason for the transistor blowing I think was a dodgey diode (broke away in my hand). I have since red up about these transitors bed found if the wires are reversed on the solonoid we could do some damage again.

So just checking the common cables to the coil ( fat cables) should be on the same side as the band in the diode?

Hope u guys understand the question. 

The diode can be soldered to the coil either way - but you are correct - the two larger gauge wires must be soldered on to the banded side of the diode.