Personally, I'd pressure check the pump and clean or replace the sock. Check the tank for sediment and clean it if necessary. At 133K I wouldn't expect you to have issues with it the pump, but it's also 18 years old. If you feel more comfortable swapping it out, you're still looking at a new pump's longevity vs. What may be OEM. I'm at 175K on my '08's pump and it's still going...