I'm using low nitro fuel(10%) in my OS LA .40. It kept running rougher the last 3 times I had it out. The glow plug still lights up so I figured that wasn't the problem. I then went to adjust on the carb (wish i hadn't went there). It's back to its original setting. I tried a new glow plug and it came to life! The old plug was an OS A8, the new plug is some generic I got from a friend. The new plug does glow brighter than the OS. My question is, do plugs go bad without burning out the element? I remember reading that if glowed it was good.