Get a lighter hammer, I actually use the flat side on the jaw of a pair of 7" lineman's pliers. Then I just tap lightly and listen, when the sound changes you will hear it, that is now seated properly. Another point to realize is that as you drill you want to prevent any wobble, if the drill has any wobble, the hole is not going to be perfectly round and that can lead to leaks too..
For this year, just let it be and get whatever you can. For next year try the lighter hammer and listen as you "lightly" tap in the spiel.
Do not pull that tap to drill a better hole, and when the taps is pulled at the end of the season, do not plug it, the tree will close the hole without your help, from the inside out.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.