Replacement Tachometer

Brought N94114 home from Batavia to S Haven, Mi and the Tach screamed in the 20degrees. Violently reacting to the cold on takeoff then bobbed at 5000 rpm for the rest of the trip. Still inoperative. Shivering at 5000 no matter how the throttle urges a true response. Any suggestions for replacement? This email address is being protected from spambots. You need JavaScript enabled to view it.