Well the petrol one broke and got stuck in ages ago and I've been lazy not replacing them then when I was messing about with the alarm one I dropped the spring ! I've ordered 2 new units today ! Car is good to go now all clean and shiny !
I had a similar issue some months back. I removed the switch and stripped it and cleaned the contacts with an electrical solvent. A little lubricant and the switch is as good as new. Might save you a few pounds if you feel confident to try this path. Good luck.