/diy/ - Do It Yourself

Does causing a spark always mean damage was done? Was probing my vintage stereo receiver to check bias, required me to insert long probes into a heatsink block to reach the emitter resistors. I powered down before moving the probe but didnt wait long for it to discharge. While unclipping the neg probe I caused a spark. Unit still powers on and runs but didnt do any further voltage readings yet. Thought i'd look around online to try and find out if spark always equals damage.
Pic related is pic I took with heatsink disassembled to better show the situation. The pincers sparked during unclipping as seen, maybe hit that lug or the screw, not sure. I have an imgur with more pics/schematic if it helps https://imgur.com/a/nt5weOi