it was the ballast & the bulb. the new bulb they gave me is way brighter& hotterI have 4 digital 600s from HTG. I burn sunmasters in them. I have had one bad bulb which they instantly replaced. I started with one ballast, and never saw a reason to replace it.
Your ballast was probably the culprit.
both ?it was the ballast & the bulb. the new bulb they gave me is way brighter& hotter