Re: do i need a new scale?
warm up is important, but not all that much if the scale is used in an area that it was stored in. Vibration will screw up readings on any scale, so you might want to watch out for that stuff. The flouresent light thing is over rated. A long time ago yes, but you also could hear the hum thru your audio system as well. So if you hear a hum thru your speakers with no music then you may well have a problem, but it's probably a ground fault loop in your house (very common by the way) Also make sure the scale sets level with the earth. I set my scales on a piece of granit I bought at Menards for four dollars. Under that I have three hard foam pucks (came in bulk CD boxes).
The Lymans are not very good in quality. The dealer I deal with quit carrying them because many wouldn't work right out of the box. The RCBS 750 is a much better one, and built in Texas. I use nothing but electronic scales, and have not owned a beam scale in close to fifteen years. No problems here