7490 mod 6 counter reset problem

Hi, I am making a digital clock using HD74LS90P decade counters. For divide-by-6, I grounded R91 and R92, and shorted R01 and R02 with pins 8 and 9, which are the B and C of the output. The output goes to 5, and then starts oscillating between 4 and 5. It works fine when i set it to reset after 10. Does anybody know how to fix it?

Can you post a schematic?

View attachment 64435

Here is the schematic. It works fine on proteus, the problem comes on hardware.

What you show works fine in LTSpice, too.
We have no idea what/where your R91, R92 etc are, but it would seem your hardware isn't wired the same as the schematic. Double-check your layout and actual component pin-out and connections and make sure the correct voltage is at the IC supply pins and has a decoupling cap.