Recently I'm looking at neuron action potentials (AP). I generally get tight seal under V-clamp and switch to I-clamp. When I switch back to V-clamp, however, I sometimes lost the seal. To switch, I turn off ex command knob for I-clamp, then switch mode to I = 0, then switch the mode to V-clamp, turn command for V-clamp on and go to V-clamp protocol. Is it correct? I also noticed that sometimes I run seal test under I-clamp and the seal seemed lost. What could be the problem? Thanks a lot.