Thanks for taking time to post.
I tried connecting to my laptop as I thought this would be the easiest thing to see what was happening and tried both joysticks.
Each joystick test came out exactly the same - it does hit all 8 parts of the box, but the diagonals seem to be very hard to hit - rolling the joysticks sometimes hits them, but only for a brief millisecond before moving on (the Down/Right diagonal on both joysticks is definitely harder to hit than the rest and pretty much never gets hit on rolling). So, I can hit the diagonals and hold them there from a neutral position - although the movement of the joystick is not exactly diagonal, If it doesn't hit the diagonal corner straight away (even though I think I'm holding it diagonal), I have to slightly move the joystick till it hits that sweet spot - that spot seems to be very small (probably only covers about 5 degrees of the total 360 you could move the joystick).
I take it this isn't normal for a joystick and the diagonals should be far easier to hit. I guess the question is, are my joysticks a load of old pants, or is this something I can change as both joysticks seem to be exactly the same? Bitcade the company I bought my cab shell from recommended I buy Zippy joysticks from ExtremeHardware - because that is what they use for a lot of their builds - and this is what I did. If I have to buy new joysticks, has anyone got any recommendations on ones that are definitely going to work, not break the bank, are available in blue & red, preferably ball-top.