They use to say that hope this dies last ...
They use to say there is no new learning of truth with out paying the price... and both sayings are true.
News in tittles.
1) Seeking for parts ? You better visit a local hardware store related or specialized to power tools first, and leave eBay as last.
2) Large box with O-ring this hides a trickery, you spent 7E and you get largest quantity of unpopular in size O-ring, and from the popular O-ring sizes there is qty of only five.
3) I succeed by visiting a local hardware store to find exact rubber shield for pistons, this is 2.5E its one, and also to get more o-rings of the popular size.
Now I have enough parts to rebuild my pump, and parts for a second rebuild (in the future).
In conclusion by a total cost of 27E, I managed to get 100% of needed parts so this APW-150FP to get back in action.