This may be what you're looking for:
https://www.ebay.com/itm/18629869390...Bk9SR6yYoa24Yw
I posted a different link earlier but realize it was probably for a different kind of 15 series pump. Please check and verify the above is correct.
I have bought from this seller before and was successful in rebuilding my pump except I needed to run to local supplier and obtain the correct size o-ring for the charge pump. Apparently, there were changes in o-ring sizes on the charge pump at some point in time.... I can't remember the correct size but I recall the correct size to be larger.