Without seeing the machine all anyone can do is speculate.Thread in the race,I very much doubt it.Wd40,never unless the machine is "gunged up" with old oil & grease.Best advise,take your machine to a local repair shop & ask their advice,any descent engineer will advise at no charge.Once you have had the nature of the problem confirmed then you will be in a better position to ask for help & provide the relevant information needed.Good luck.
Ben
February 2011