Pianist's bane

One of the many banes of a pianist's life is a squeaky sustain pedal. And the propensity for machines to get into a state where they squeak, chatter or vibrate seems to be a general issue of which the piano is but one instance.

To aide my sanity and make profitable use of my spare time whilst in Devon I have invested in an Alesis Recital Pro piano keyboard. I am generally very happy with this machine even if it is no match for a real piano, but as it came without stand or sustain pedal I have improvised on each and my pedal design is shown below on its side.

My foot presses the darker plywood pedal which is hinged to the base and operates a small microswitch. A helical compression spring is located in a hole drilled in the base, but there is no matching recess in the actuator. Yes, the microswitch clicks and this is annoying but, worse, the mechanism in general develops a squeak over time which could be caused by the spring, or the brass hinge, or the microswitch lever rubbing against the pedal. It's hard to know which because upon investigation the squeaking promptly stops. Short of a major redesign, my present recourse is to apply oil to all of the above. But I'm pretty sure that sideways motion in the pedal allowed by slack in the brass hinge puts the spring off centre and which then rubs when the pedal is depressed and causes the squeak. if so the solution would be to use a more precise hinge.

Oh, and in use it tends to walk across the carpet ending up abutting the piano stand and thus either not working or scraping the stand when depressed, so I have now affixed it to the stand to stop that happening.

Squeaking is caused by stiction when one surface rubs against another. The two surfaces stick to one another until the sheer force is strong enough to overcome stiction. The surfaces now slide until the force reduces below that of friction. This typically makes a "tick" sound, but if it repeats frequently enough it becomes a squeak. Related phenomena are vibration caused by imbalance or backlash in rotary mechanisms, and chattering in a very loose bearing. In each case there is unwanted movement, doubtless caused by excessive manufacturing tolerances. I can well imagine that my spring might wander in its locating hole or go out of plumb and thus slide across the ply actuator and generate the squeak. 

But what interests me here is that parts of a machine will move (if given liberty) until they find a position in which they squeak or vibrate, and then stay there. Why should this be? Is it the propensity and perversity of nature as in if a thing can possibly go wrong then it will and moreover will generally choose the most inconvenient time to do so. Or is it positive feedback which exacerbates the effect?