Tic Toc Tach sticks @5500 RPM help

[slim17265]

finally got 440-6 pack on the road thanks to Scott Prestons help with my many wiring issues. So far this car is not all I thought it could be although it seems to make decent power to 6000 rpm. This 6 pack set up is rife with problems,leaks,maladjusted parts. But now on its first maiden run the tack pauses slightly at 5000 then sticks @5500rpm and refused to move for some 2 miles. I believe there must be some electrical sending unit somewhere hopefully because I do not see any evidence of the tack needle sticking anywhere within its housing. thanx in advance