The Barcol Impresser is a simple instrument with very little to go wrong. The indenter point is usually the most vulnerable part becoming worn or damaged in use. Usual symptoms are that readings are much higher than expected, and on the 934-1 Impresser, it becomes impossible to achieve calibration with both calibration disks. The indenter points are easily changed but cannot be repaired or reground. The 934-1 and 935 impressers share the same indenter point but the 936 uses the GYZJ 67 point which has a different angle.
