Hi Chaser,
The way i undertand it is that some leak off is normal.
Measuring the ammount of leak off on each injector, can indicate which one has problem.
I've just been reading a PDF at rover rons thats says that they should all be re-conditioned every 100k miles. I know that mine have not been done in the last 122k, I doubt that they were done up to then.
I might just get a quote on changing all four.......£££££££
Cheers
David