That's a really kind offer, thank you. To be fair to you, how about I pay you (say) £10 for the old one plus the cost of postage and I'll take the risk as to whether I can get it working or not? If that works for you, I could pay you by paypal? Maybe we could arrange by phone - I'm on 07747 781666.
By the way I had another heart-warming offer from someone on this forum offering to fix the little switch itself for me and return it by post so I've now received two random acts of kindness in the same week - what a great forum - many thanks all - Rich