Did you work out for yourself which one wasn’t working or get someone to do that for you?

I built a little leak-off test rig out of some plastic bottles and some hose- probably pretty much what the garage has done, from your description, so I reckon you’re past that point but I think my email’s in my profile if you want to know more… Nice simple stuff and pretty pleasing to do, it’s like milking the engine 🙂

Once I’d found the faulty one I didn’t go down the testing route- it was £40 to test, then £100 or so to do a full refurb so the cost was damn nearly the price of a new part anyway.

Have to say, I don’t know enough to say if it’s your fault though, mine actually always ran very nicely- it just smoked like a mofo and wasted a lot of fuel.