Make the jump to double ended bulbs and don't look back. I've been flowering nonstop for 30 months under my gavitas and still pulling 2+ per light with them set to 750 watts.
I would buy a new one, i always have a back up of almost every thing, pumps, bulbs etc etc.
point is, i bet if you put the new one in next to the 4yrs old bulb you would see a big difference. you don't notice the bulb dimming with age unless it's next to a new one.
but I'll bet the new bulb smokes the 4yr old bulb
if not you have a back up and and I'll damn sure will be buying ushio
Make the jump to double ended bulbs and don't look back. I've been flowering nonstop for 30 months under my gavitas and still pulling 2+ per light with them set to 750 watts.