My mountfield sp474 conked out after about ten minutes now it wont start?

I topped the oil up the other day, checked the fuel and the filter, no debris in plug cover.
It only worked for a while then stopped, felt like no power in it.
My son tried yesterday when I was in work and same thing happened. Unfortunately he let the pull cord go back fully into the engine casing and I can't pull it out at all. Seems stuck!
Any suggestions how to pull it out?