Right, well, after having another fiddle, the car will now select 5th and reverse, IF, i am under the bonnet pulling the gear selector straight up a little bit when someone else is inside the car selecting 5th or reverse gear.
Basically, the gear selector is meant to start at the bottom position for 1st and 2nd, goes up a notch for 3rd and 4th and then up to its highest point for 5th and reverse, but, it isn't raising itself high enough to engage 5th and reverse...
Does anybody have any idea why this may not be working? there is a spring but thats in properly, also a balanced weight which is all on right etc, everything is as it was when it went on.
The only thing i can think is that the Z shaped selector that slides into the shaft (the reason for the stiff gear change) needs to be removed and repositioned a notch further round? although this is (un)educated guess work.
As always, all help much appreciated!!