if you look at top of g/box where the two cables are attached,get someone to move gear lever from first to second and watch the selector shaft move up and down,if you have a lot of brown residue/rust round about that shaft then apply a lot of oil/wd40 and keep working the gears from 1st to second.It may take five or ten minutes but persevere and hopefully it will start freeing off,get it moving across neutral,then in the other gears.Keep applying some lubricant throughout the year and it won`t seize up again.If it doesn`t free off then you may need a selector housing,try a scrappy as they are expensive.
cdc
January 2013