I had the exact same problem on my 58 beetle; jumping out of reverse as soon as load was applied.
I had Pete of 'Cogbox' sort mine out, he replaced the main shaft that incorparates 1st and reverse gears with a good secondhand one as the gear lobes were vell worn. I guess this was partly due to there being no syncro on 1st and reverse.
Been as good as gold since:d
harveypj wrote: