I replaced the regulator on my 68ci paintball tank with an inexpexsive 4500 to 1800 psi regulator off of amazon. I haven't used it that long but so far it's working good. I didn't care for the coiled hose on the valve setup I bought so I switched it our with a long straight hose I had. I also had to buy an inline bleed valve otherwise there's no way to bleed the pressure from the hose to remove it from the gun.
When replacing the regulator you only need to hand tighten the new valve, the tank pressure ensures the valve won't unscrew.