I use 3 of them. One comes in at the bottom, the other 2 I have running in at the top. You are right, the top inlet was for washing only in a dairy application. I prefer the top and assume I get a wee bit more vacuum transfer. (less restriction).
As far as the air leaking, new seals should do the trick. If the glass is chipped a little, then it probably won't help much. In that case, I smear the top, inside and out liberally with vaseline. put the top back on and then smear the outside of the seal/jar with more. Hasn't failed yet.
Mark
Where we made syrup long before the trendies made it popular, now its just another commodity.
John Deere 4000, 830, and 420 crawler
1400 taps, 600 gph CDL RO, 4x12 wood-fired Leader, forced air and preheater. 400 gallon Sap-O-Matic vacuum gathering tank, PTO powered. 2500 gallon X truck tank, 17 bulk tanks.
No cage tanks allowed on this farm!