Letting a gaited horse pace is encouraging a bad habit. If changing the saddle does not solve the problem,and you still like this horse lease, do a ton of bending. At a standstill, gently bring the horse’s nose back to your knee on both sides, many times. Step in a very tight circle, almost on the spot. Do the ribbon-candy exercise down the long wall. Pacing is often a sign of a very stiff back.
My gaited horse will offer a pace when he has not been ridden for awhile. I do the bends above described, and I can hear audible cracks in his neck and back. Then he will gait as normally.