Gearboxman is the best solution and you are the cheapest one. Not too difficult really, if you want to learn something new. Wha tdo you mean with "crunching into"? Only trouble engaging gears or do you get constant noise? Anyhow, when you open a faulty box the fault is in most times obvious to see. Since you have a S1 box, it's also really easy to just buy a sound which ever gearbox and just change the LSD from the old box to the new one.