hows it going.. i'm pretty much mechanically illiterate but i'm having troubles (only sometimes... probabley 40% of it..) getting into 1st and 2nd.. the other gears are fine... if the car is turned off.. there are no problems (is this because of the engines load on the gear box)...
..just wondering if the gear box is coming to an end or if any one might have some advice... what sort of cost for a rebuild or a replacement.... thanks very much....

Actually, the first thing I'd check is the shift rod bushing and adjustment. But do it soon, if they're out, the shift forks will wear excessively.

I agree with 70autostik, but also if it only happens with the engine off, i'd check if a bad clutch is to blame (just speculation, fingers crossed).
Good Luck