Quote Originally Posted by clough42 View Post
Something else must be wrong. I'm using a sub-$3 HXT-900. I buy them by the dozens and use them for everything. I've never had one fail.

Is the servo staying on, struggling against a mechanical stop or something like that? That could certainly damage it. You might also check the voltage to the servo. If it's over 5V, that could shorten the servo life.
Specifically: Check and make sure

#define PROBE_SERVO_DEACTIVATION_DELAY 500

is defined and has a reasonable value in it (500 to 1500 should be OK)