Foredom hammer handpiece 15

I bought the LX foredom with hammer handpiece 15 about 18 months ago,
I use this handpiece only a few times a month for stone setting,
today when setting about 12 cabochon stones in a bracelet all went
fine till half way, suddenly it became to hot to handle, it takes a
few minutes and I have to stop to let it cool off, the handpiece is
maintained as per the manual. In the archives I found some issues
like this but the handpieces were old and frequently used. Anyone who
had the same problem? I have send also an email to Foredom, but
living in Spain and having to finish the bracelet I am in a hurry, so
anyshort cut to solve my problem?