A resistant mechanical combination lock and improvements thereto is described herein to include one or more of the following features: an improved combination change/set feature including a tumbler interlocking lever (132, 133) with digitated micro-fingers (135) for interdigitating with digitated micro-fingers (131') on the peripheral edge of a combination tumbler ring (131), the lever (132, 133) and the ring (131) sandwiched between outer gate rings (130a, 130b) to form a tumbler wheel assembly; a key stabilization feature in which an internal boss (126) and a pivot recess (125') together help stabilize the change key (122) when changing the combination of a lock to help prevent "lock out"; an improved duress feature including a duress tumbler wheel assembly (200, 250) (including a duress lever (201, 251)) and an interchangeable microswitch (220, 270); and/or a fence control feature preferably including an overcenter spring (330) and trigger plate (333) for controlling fence contact with the drive cam (308).