I'd have to agree with you on that Geoff but if you don't include the team leader that's how many there are in my section. If anything if two does work as long as no one goes off sick.
I must admit when there was three people I did have to read a good book, but I personally would say you need techs working at 60% capacity but I do know other places where they either work at lower or higher.
Problem is some MES companies would actually say that the right number of techs in a small hospital like this would actually be Zero. Instead of actually having anybody on the ground you have one clerical person who just packs the faulty equipment into boxes and ships it either directly to the manufacturer or to their head office where a small number of techs work on multiple sites equipment.