My scale shows that i weigh about 30 pounds lighter than i do.

Contact Avery for a local repair facility. This is interesting!

https://www.industry.gov.au/sites/default/files/nmi/certificates-approval/6_4A_3.pdf

I remember this scale as a kid in the 1960s buying 2 ounces or a quarter pound of sweets.

https://www.google.com/search?q=Avery+1215+BFH+Weighing+Scale

Avery Weigh-Tronix

Avery Weigh-Tronix https://www.averyweigh-tronix.com Avery Weigh-Tronix is one of the world's leading suppliers of weighing scales, systems and equipment. We offer a wide range of industrial weighing systems and ...

1. Place the scale back on a hard surface floor.
2. With one foot only, place just enough weight on the scale for the display shows zero's or dashes. Once you see zeros or dashes remove your foot.
3. Wait for the scale to turn off again.
4. Step up onto the scale for a weight.

check at the back of the scales for an adjustment screw or knob
to make the adjustment you will need items of known fixed mass over say 2 lb to 40 lb
you can do this by accurately measuring 1/2 gallon , 1 gallon 2 gallon 4ga;;ons of water as it is 10 lb to the gallon
there may be a pdf version download on the net if you go google and type in--- user manual for (make and model ) scales

Sounds silly but check the scales for a Kilogram or Pounds switch. its usually under the scales and is a sliding switch. It should tell you on the display if you are weighing in pounds or kilos.

Are you talking 31 "Stone"? If so, I believe that comes out to 434lbs. You are lucky if your scales can read that high. For testing purposes, remove your shoes or more if you think your right at the upper limit. Or let a slightly lighter friend try it. I assume your talking "Stone" as used in the UK. Are you from there? (I,m in the US, in Florida.) Also, there should be a switch on the bottom of the scale (upper left corner) allowing you to switch between lbs, st and kg. You can try that as well, although the limit should be basically identical. If you tell me more, I can help you more.
(By the way, I weigh 197 lbs right now, that's 14 stone.)

Put 3 balls on each side of the scale. If the scales balance then weigh the remaining 2 balls and this will show the lighter one. If on the first weigh (3 balls each side) the scales do not balance- then take the three ball from the lighter side and put two on the scales (one each side) and keep hold of the remaining one. If the scales balance then you are holding the lighter ball. If not the scales will show which is the lighter ball. You can use the same logic for up to 9 balls.

Take a 5 pound bag of sugar, flour or what have you. Put it on the scale. If it is off, turn the scale so that you can check every possible place for an adjustment. Adjust and go for it!!! Good luck...Lee

The scale must be on a hard, level surface. Make sure there is absolutely no dirt on any of the pivot points. Calibrate it with a KNOWN 25 pound weight.

Operating Instructions1

A. Powering-on the scale
1. Press and hold the POWER button for two seconds. Scale will perform a self-test by displaying four 8s for three seconds. When "0.00 kg" or "0 lb 0 oz" is displayed on the screen, scale is zeroed-out and ready for normal operation.
B. Normal Weighing
1. Hang fish on the attached hook. Weight is displayed in either kilograms or pounds and ounces.
C. Switching between unit weights
1. Press and hold the POWER and CHOOSE button simultaneously for three seconds. Unit will change from weighing pounds and ounces to kilograms and vice versa.
D. Taring Weights
1. Weigh a bag or container till its weight is steadily displayed on the screen.
2. Press the POWER button once. Scale will zero-out and show "0.00 kg" or "0 lb 0 oz" and is ready for weighing multiple fish together.
E. Holding a weight
1. With the weight displayed on the screen, press the CHOOSE button. This will hold the current weight and is indicated by displaying an H to the left of the screen. To unlock the hold, simply press the POWER button.
F. Storing weights into memory
1. With a weight in the hold mode and an H displayed to the left of the screen, enter the memory mode by pressing the CHOOSE button. While in the memory mode, pressing the CHOOSE button will allow you to navigate through ten stored memories. These are indicated on the left and numbered 0 through 9. There are also 4 letters that indicate other options. An A shows the average of all stored weights. An E displays the total and a C resets the memory.
2. To store a weight, simply hold down the CHOOSE button for three seconds. Weights will automatically store into one of the number registers. To see the numbers with their weights, simply scroll through the numbers by pressing the CHOOSE button as described above.
G. Resetting the memory
1. With the unit in the C mode, press and hold the CHOOSE button for six seconds and scale will reset memory and zero out. Press the POWER button and scale is ready to begin weighing again.
H. Powering-off manually
1. Press and hold the POWER button for 6 seconds.

Hope this helps,plz let me know
JonnieC


Weighing 1

Weigh 1 2 3 on the left and 4 5 6 on the right

If the weights are even go to Weighing 2a
If the left side is lighter go to Weighing 2b
If the right side is lighter go to Weighing 2c


Weighing 2a

Weigh 7 on the left and 8 on the right

If the left side is lighter then weight 7 is the answer
If the right side is lighter then weight 8 is the answer


Weighing 2b

Weigh 1 on the left and 2 on the right

If the weights are even then weight 3 is the answer
If the left side is lighter then weight 1 is the answer
If the right side is lighter then weight 2 is the answer


Weighing 2c

Weigh 4 on the left and 5 on the right

If the weights are even then weight 6 is the answer
If the left side is lighter then weight 4 is the answer
If the right side is lighter then weight 5 is the answer