Calibrate salter balance


Is there a way to calibrate a salter balance, it is showing an extra 70g on every weight I try, I've put a picture in that shows what I mean. Anything I can do to save it, maybe a new battery?

Thank you

Interesting question - I have a balance doing something similar - an ohaus traveller that is needs 200g on it to get to zero!
wont even pass startup without it. I have kept it as a curiosity and in the vague hope I may come up with a solutions someday.
Not sure about Salter, but Ohaus have manuals available online. This will have the instructions for calibrating.
If only it were that simple - I have the manuals and the other 5 calibrated beautifully. This one needs 200g or fails at testing when you turn it on. I n both cases I suspect someone overloaded the balance by a large amount somewhere in the past. If there is a slater manual you should be able to calibrate, mine i think needs something replacing or straitening.
This place has some salter manuals if you know which it is: