Just want to thank the "OP". My 40 year old toilet has been sluggish flushing for a while, often needing two flushes. Read this thread, got to checking and sure enough the water "siphon" hole as well as the 16 little water jets under the rim were partially clogged. Used the Zep brand of "CLR" in a spray bottle around under the rim to loosen the mineral deposits, and poked a right-angle scribe tool up in the holes to clean them out. Used a piece of 8 Ga wire to clean out the siphon hole. Flushes like a new one now. Thanks again!