OP

Quoted from jrawlinson_2000:

Thanks for the assistance.
Upon investigation I indeed found the Goblin switch to be too sensitive, so I enlarged the gap, I also noticed that when the beasts pop up they sway as such have been triggering.
I also found that if I pushed the mechs up by hand the Spider mech was not as smooth at dropping as the other three beasts, I could not really see a where it was catching.
I therefore detached the plunger to at least isolate the mech or the plunger runing through the coil plastic, both appeared fine, so I reassembled only to find the mech would no longer go up by hand.
In the end it appeared that the nut that kept the plunger attached to the mech needed to be a tad looser, then the mech worked and runs as it should do, it must have tightened over time.
Anyway all working now so thanks for assistance all.