Carl lewis jogging machine not working?

I have a Carl lewis jogging/running machine.  Its kept inside at room temperature but not been used for some years.
Went to go on it the other day and after about10 minutes it gradually slowed down to a stop. I lifted it up and manually pulled the belt the opposite way and it freed it up.
I went on it the next day and had the same problem I tried increasing the speed which seemed to work for a few seconds but then there was a thud and it stopped working all together. Any ideas of what the problem could be and how to fix it please?
Many thanks in advance.