Fiesta st gearbox or helicoil?
 

My fiesta st 2006 has stuck in 3rd gear, I been told I need a new gearbox but a mate says I only need a new helicoil to fix damaged threads, any advice on what to do?

Your question is a bit vague, Is the damaged thread part of the gear selection mechanism? Any pictures of the damaged thread?

Fiesta st gearbox or helicoil
 

Yes it is part of the gear selection mechanism, I dont have any pics at present, it is still in the garage, is that any help?

Well if its just a mounting thread inside then yea just helicoil the damage or fit a threaded insert if enough material!!

Assuming nothing else is damaged inside!!

Nothing wrong with a helicoil mate, they are common in alloy components in high strength applications from new.

The helicoil is the cheap option, worth a go before you spend a fortune on a new gearbox ;)