i have two servos, JX PDI-2506MG, that can only be driven between ~45° and ~135°
makes a rapid clicking when attempting to drive past these values.(guess: motor is oscillating to hold position)
mechanically it is capable of doing ~0° to ~180°.
i'm testing with the stock sweep sketch,it is producing the correct timings.(confirmed by scope)
a known servo,a JX 6632MG, in parallel works as expected.
internal pot appears to give approximately correct values for various angles.