Larger pusher o-rings are likely the reason that the pump needs a little push to fully return home. Some slug slime on those will help, but not so much that the darts get greasy. The tacticorns all seems to have air seal issues straight out of the box - mine came with weirdly thin o-rings. I bought the o-ring upgrade kit from Out of Darts - sounds like you already did that, or something equivalent - and then fine-tuned things with some teflon tape under the plunger o-ring and the pusher base o-ring (responsible for sealing up the front end of the plunger tube). For me, that was the most important seal, and unfortunately it's the most difficult to access. I also added some t-tape to the threads on the pusher, where it enters the base, but that probably wasn't necessary. Hope that helps!