Jet scroll saw problem

[Trka2002]

I’m having trouble with my saw and can’t figure it out. I have my speed set, and while cutting, the speed picks up and then slows back down. Almost like if you where in a car, hit the gas, and let off the accelerator. I don’t use a foot petal, so that’s not the issue. Please, let me know if you have any ideas. 

[Newsawontheblock]

I have had the same issue with my EX-21. The first time it happened I removed the top plastic piece and checked for lose parts. Didn’t find anything so put the plastic top on again. Saw ran normally for quite a while. When it happened again, I blew compressed air into the space by the top arm. Saw settled down again. I found if I ran it at full speed it generally pulsated, so I always ran it at a little under full. 
The saw was practically brand new when I bought it, after a while it seemed to break in, and I could run it full speed if I wished and it would act fine. Not sure how new your Jet is, but it could just need broken in.

[Woodmaster1]

It is an issue with almost all Dewalt, Delta, Excalibur type saws. The potentiometer just doesn't work the way it's designed to. I don't if it's the circuit board or the speed control. Find a sweet spot and leave it there.

[Fedido]

Like new saw said, maybe needs to be broke in, but before I take a stab at it, does the acceleration occur when your not cutting wood? Also, does it occur at different speeds like that? I don’t own a Jet, but these are an attempt to isolate the problem. I have a Dewalt 788 Type 1 and I can run it at any speed without any problems. Just my two cents.