The devise marked by 5A but internal configuration
resistor Rd1 is 402R - for 1A.

LM336-2.5, CA3130E, Z1 36V, D3 1N4148, LM334Z, R6 100R
Corrosion, repairing the terminal. 
Making full circuit.

Calibration:
0...1A
4...20mA