hI , GOT A 16V 1.8 1989 G , having real hassle selecting reverse , it will go in with a real shove but it makes the tarnsmission crash into gear , all other gears seem fine a touch notchy but i think they are like that any way, could it be oil ? could it be linkage ? could it be just a knackered box ? its done 120k miles can some one help as ive been quted £530 to replace it and i really dont think its the box , but im sure someone on here can help ? thanks :D