Singer 1525

Question

I have a Singer Model 1525, I got it to replace a 25 yr old White that constantly needed retimed. It's a very very basic machine. However there is now a problem when the handwheel and belt spin quite well but the rest of the machine goes slow as dirt. I can press the pedal all the way down which should send the machine into a flurry but instead the dog feeders, needles and everything just go super slow. Is this a timing issue or something else and please, how do I fix it?