gearbox 1st missing

hello
i have a series 3 and the main baring in the gearbox is going
i know they can live some time with a little noise coming from it
i have the original gearbox but 1st gear never worked (that's why i got a another one but never got round to fixing it) so does anyone know what would cause this problem it feels like it is selecting the gear but you lift up the clutch and theirs no drive all the other gears are fine at the moment this gearbox it out and if i can fix that problem than ill put the old one back in also i have un seized the handbrake drum but cant get it off any tricks on that as i would think the insides would need replacing by now i haven't any experience in gearboxes i try getting the top cover off but i think i may be missing something as it still inset coming off after taking all the nuts off
thanks a lot

Top cover probably needs a wack. Removing the t/box will help access to the cover.
You can't remove gears from the top, you can only take out the selector forks. To remove gears you need to remove the front and push the shafts out. A manual would be handy.