btw, I don't get how a Pitot obstruction only (of the ram port/the drain) can lead to overestimated airspeeds (and possible overspeed alarms)
ram port + drain blocked during climb means (almost) constant ram pressure together with decreasing static pressure, leading to overreading of airspeed. Experienced it once in a Piper Seneca (FIKI approved) with malfunction of pitot heat (it worked during ground check before and after, but heating power was obviously low).