The sprayer for some reason is now pulsating, so the spray is no longer consistent. Anyone know of an easy fix? If not, who to go to? I purchase the system used.

Depending on model you have determines the cause.
But the most common issue is the check valve that the pump pushes against is sticking or has debris stuck in it. This little check valve closes when the spray pump is cycling. The pulsating issue is the pump pulling and pushing against the high pressure side of the pump. It should only push against it. But when the valve sticks some of the higher pressure moves back into the pumping area thus causing the pulse your speaking of as well as very low pressure at the gun. In some cases the pump will not even pick up the paint from its hose as it will not prime.

No matter how well you clean the sprayer this little valve gets gummed up and starts to fail
You need to remove this little spring and small ball bearing valve and clean it real good. You should see a fitting where the spray hose attaches. You may need to remove a larger fitting to expose another fitting located behind this hose connection. An allen wrench is typically used to remove on most sprayers.

A little oil on this after each cleaning goes a long way in preventing this from causing issues when you go to use the sprayer again.
There are liquids you can purchase at most home centers and rental centers that you pump into the sprayer after its cleaned to prevent any left over paint that is still in the pump system from getting hard.

Thanks. It is a model 10.14, I believe. I am trying on line to find a manual for it with a parts listing.