So I have built the circuit and it works!
, I first tested the inputs using a couple of 1.5v AA batteries and they triggered fine so the next step was to try it on an old donor PC. I plugged it in and switched it on and the solenoids engaged. Oops, back to the drawing board I thought.
I decided to check the voltages on all the pins during boot and i found that Pins 2,3,6 and 8 were high during boot while Pins 1,4
,5 and 7 were low and seeing as Pin 4 is the disable pin it needs to be high during boot time. All pins are high once windows loads.
I switched Pin 2 to the disable line and pins 3 and 4 as P1 and P2 recoils and it boots fine with just one short activation just as windows loads, I can live with that. I also notice that if I open 'My Computer' it also briefly activates the solenoids???.
I loaded up Mamehooker and tested the script lpe 1 3 1,lpe 1 2 0,wat50,lpe 1 3 0,lpe 1 2 1
and it works fine, I tried to run Terminator 2 in MAME but the donor PC is just not up to the job so I think I'm going to have to start ripping my cab apart to fully test it, Obviously I will have to check which pins are high on my MAME cab to find out which ones I should use.
Anyway, it seems to work and although it isn't going to be a one shoe fits all it is still possible for anybody to use this circuit as long as they have one pin that stays high during the boot process and once windows loads.
Thanks for the help, Once I get it running in MAME I will try and get a video of the solenoids in action. My soldering isn't the best but it does the job.