Which instrument discrepancy would require replacement of the instrument?

Which instrument discrepancy would require replacement of the instrument?

• A. Cracked or fogged glass, will not zero out
• B. Intermittent ruler marks
• C. Spurious red warning light
• D. Drift within tolerance

Answer: (A)

The key idea is that any indication of moisture or damage inside an instrument that affects how you read or trust its output usually means replacement is required. Cracked or fogged glass indicates moisture ingress and a compromised seal. This not only makes the display hard to read, but it can also alter the internal workings and calibration in an unpredictable way. Once moisture is inside, you can’t guarantee accurate or safe readings even after attempts to repair, so the instrument is typically replaced. The other issues can often be addressed without replacing the instrument: intermittent ruler marks suggest a mechanical contact issue that can sometimes be repaired or recalibrated; a spurious red warning light may be a faulty indicator or wiring that can be fixed; drift within tolerance means readings are still acceptable and can be corrected through calibration.

The key idea is that any indication of moisture or damage inside an instrument that affects how you read or trust its output usually means replacement is required. Cracked or fogged glass indicates moisture ingress and a compromised seal. This not only makes the display hard to read, but it can also alter the internal workings and calibration in an unpredictable way. Once moisture is inside, you can’t guarantee accurate or safe readings even after attempts to repair, so the instrument is typically replaced.

The other issues can often be addressed without replacing the instrument: intermittent ruler marks suggest a mechanical contact issue that can sometimes be repaired or recalibrated; a spurious red warning light may be a faulty indicator or wiring that can be fixed; drift within tolerance means readings are still acceptable and can be corrected through calibration.