If you find that your gearchange is stubborn, notchy or otherwise difficult one really easy thing to do before you panic and take it to a garage for a possible gearbox replacement is the following:
Get yourself a can of brake/clutch cleaner spray, some old rags, some technical grease and a handful of time. Lower the spare wheel, take it out and then peek up into the space you've just opened. There you will see the guiding mechanism for your gearstick. If this looks very dirty and sticky, you've found yourself something to do

Liberally apply the brake cleaner and then patiently remove all the gunky, sticky, gooey old grease and dirt of the last 20 odd years. (Did mine last Sat. ...it didn't look bad at first glance, but it was so sticky, that when you pressed a screwdriver into it, it just stayed up there all on its own)
Once everything is shiney and clean, apply some fresh grease (let someone else move the gearstick around) and make sure it sits everywhere it needs to. Now enjoy your slick, new gearchange.
In case there is no slick, new gearchange feeling, you're sh*t out of luck and had better read THIS
