My experience is that it is almost impossible to get the glass-bowle OK. It will leaks air.
I have installed an electrical lift pump and have had no problem what so ever. I kept the mechanical lift-pump and installed a HCO suction pump giving a slight prime pressure and have had no problem since that. Between the tank and the Hco pump there is a one way valve installed. Of cause I replaced all possible hoses. The return to the tank now shows a steady flow. My tractor is 4340 almost the same as 6245. If you not bypassing the mechanical lift-pump 2-3 PSI is what you need. 10 is to much.
I also replaced the glass-blowle filter with a Malpassi Water-trap. My tractor has worked perfect for 300 hr since that.
If somebody interesting I can deliver some photos of my installation.
Please ,make sure that the tube bend from the tank isn't blocked, a classical problem.
Hazze