A system for monitoring a condition of a consumable component in a substrate processing system that includes a tapered plug having a first axis, a second axis that intersects the first axis, a top portion with first width, a bottom portion with a second width, and sidewalls joining said top and bottom portions respectively. The tapered plug has a cross sectional profile that is substantially parallel to the top and bottom portions and a cross sectional width that varies according to a location where the cross sectional profile intersects the second axis. At least one of the tapered plugs is inserted into at least one consumable component of the substrate processing system such that the top portion of the tapered plug is exposed to a processing environment of a plasma processing system.