Booster pump (PB4) seal leak

[Poconos]

If you're sure it's the seal assembly I'd replace it and the other two parts while in the thing. The way you stated the question you were looking to just replace the O-rings. P-55 is the seal assy. Anyhow, are you sure it isn't just the large O-ring that is leaking under pressure? My Hayward pump is similar and the one large o-ring leaks every spring, then I tighten the 4 bolts and it stops until next Spring. It's finally squished enough I'll replace it next year...already bought a new one. As to how hard it is to replace? Don't know, never had to do mine yet, but it doesn't sound difficult at all. Some comments I've seen on this forum over time relate to bolts rusting and seizing on equipment that is exposed to the elements.
Al