coupling capacitor ina114
I must take Audiogurus part now and post a LM741 comment first. It's not just lousy, it's specified for minimum supply voltage of +/- 5V. Input common mode range and output voltage swing at +/- 3V supply are near to zero and may be none, at worst case. Thus, there is no guarantee for the second stage to operate at all. Considering some offset voltage from the electrodes and the missing high pass, this may be a sufficient reason for the circuit to fail. Another reason may be common mode overload by interfering voltages.
Two electrode monitors are typically used for simple portable applications. This implies, that you don't connect a mains operated desktop oscilloscope, that introduces interfering voltages just by grounding the circuit. But I'm only guessing. Basically, the reason for failure can be found by tracing the signal with an oscilloscope, provided, you understand INA114 specification and behaviour.
Cause the problem may be related to DC input voltage, you can try a capacitive coupling (several uF non-electrolytic capacitors) of the inputs.