Reverse gear selection

I am struggling to get my 02 Disco manual into reverse gear? If i push to the right then down their seems to be an obstruction, if I then wiggle it I can eventually find the gear. The other gears are at times a little tricky but they all seem in line. Could it be a bias plate adjustment or is it more serious? Thanks in advance

You might get told that's there's another problem but I'd change the oil first, they do seem to clogg up when the oil gets old.

unlikely to be bias plate unless bits are jamming lever,to check remove consol and rubber gaiter x 2 ,do you get click sound when going into 5th and coming out and pushing lever over to left,thats rev interlock plate stops you going from 5th to rev,when checking other stuff slacken rev switch rear top passenger side to see if thats jamming ,5th gear dog teeth commonly loose front edges making shift difficult

It could well be the bias plate, thats certainly where I would be looking 1st. Only a bit of stripping out to find out, not rocket science.