Just another alternative: My archer tach cable did not break, but the tach under reported rpm significantly at high rpm, not a great situation when properly leaning at high power settings. My solution was to retain the analog tach, to retain as a primary gauge, and put in the EI FP5L fuel flow gauge/totalizer, and added the digital tach option, which can not be used as a primary for rpm. Yes this is more money, but the added fuel information, especially when connected to your GPS, is so invaluable to peace of mind on all your significant cross country flying.
Also, I tend to look at the digital readout of rpm without issue and only use the analog tach for judging run-up difference on each mag.