Mine has a plastic cover around the gold part that really blocks the view and that I am reluctant to remove because of risk of misalignment. A dental mirror does not help much. I do not know how far in a spring could have gotten because the spring and the gap are so similar in size. What I did to check travel was to tape back the spring arm on the right and unlatch the left side lower coil latch with a paper clip. Then with another paper clip I advanced the head assembly gently full forwards by pushing on the plastic rider on the right hand side wire guide. With the coil and arm full forwards you can see the two heads and the REALLY tiny wires, very important not to touch these. If you get to full extension you can see what looks like the front half of a tiny integrated circuit exposed in the front cutout of the top gold plate and exactly 3 cm of arm will be exposed. There should be resistance only in the first .5 cm of travel, after that just tipping the assembly should move the arm. When you fully retract the heads they will spread at the last moment to separate then come to rest on the head rest pad.