My seiko is keeping good time but the second hand jumps two seconds then hesitates for what seems to be a second then skips two seconds again

There are three solutions for this problem, contingent upon the model:

With both instances, this is a power saving / low charge / low battery feature of the timepiece.

1) Is your Seiko watch a Kinetic / Solar model? If so, your watch contains a capacitor. The capacitor may be bad, OR if you have not been wearing it on as regular a basis, wind the watch (Kinetic) vigorously for 5 minutes, and if the second hand returns to normal function, the capacitor is most likely fine. If is is a Solar model, expose it to sunlight for 4-6 hours or incandescent light for 24 hours and see if this resolves the problem.

2) Else: if this is a standard battery operated watch, take your watch to an authorized Seiko repair center, or Certified Master Horologist. Make sure that the Seiko Repair Center is using Seiko batteries, else make sure they are installing Energizer only - these two batteries will not leak in your movement. Avoid other batteries at all cost, many of them will leak and ruin your movement.

3). If these solutions do not work, and you have not had your watch serviced in the last 3 to 5 years, you need to service the movement. See the aforementioned parties to begin the process.

4) If your watch is water resistant, and/or you plan on wearing it in the water, make sure to have your watch water tested by the appropriate aforementioned professional to ensure it will withstand proper dynamic and static pressure at the appropriate depths.

Using only Energizer batteries is nonsense. Any well-known popular battery
will work and provide good service!