OK; so here's the long and short of it
RCBS says it's waaaay out of warranty, so try the "Love Tap" :
" During the use of electronic scales over the course of a day, you may notice your RangeMaster scale's readings begin drifting or not returning to zero. This can be caused by changes in environmental conditions, especially temperature, and also residual stresses in the load cell from manufacturing. First, verify that your unit has had sufficient time to warm-up (at least 20 minutes). If you have been using your scale for more than an hour and noticed this behavior, try re-calibrating your scale, especially if you are outdoors or in an uncontrolled environment (garage, shop, etc. without air conditioning). Otherwise, your load cell may need to be stress-relieved to eliminate these symptoms. Normal use of the scale over time will break-in the load cell and cause these symptoms to stop, but could take hours of use. Follow these steps to safely accelerate this 'break-in' period of the device and eliminate this problem:
Accelerated Break-In Procedure:
1. Remove weights and pan from platen
2. Press 'ZERO' button
3. With your finger, tap the platen softly enough to barely cause the scale to overload (you will get an "OL" reading). The amount of force required will be comparable to how hard you push on a computer keyboard when typing.
**Note** the scale is equipped with a mechanical stop on the load cell to prevent it from being over-stressed. However, applying excessive force could still damage it. Do not hit your scale with more than 8 ounces (250 grams) of force.
4. Repeat this tapping 20-30 times. (You do not want to see OL)
5. Allow your scale to stabilize. If you have a non-zero reading, your scale did have residual stress in the load cell and should function better now.
6. Recalibrate the scale and resume normal operation.
7. If over time, you notice this behavior recurring, repeat these steps again as necessary. "
Well, it didn't work
So I tore-off the "VOID" sticker and unscrewed the Face-plate
Lightly drug a Screwdriver across random Solder Joints; thinking maybe it needs to discharge static or any residual charge
Plugged it in and voila 0.0
Calibrated and working
Don't have a clue as to what it did, but the Scale works !
Thanks for all the input