Most tanks that were put into surpluses have certain parts removed from them to prevent anybody who buys one from firing the main cannon. However it doesn't prevent you from driving them...
That's why some people in America bought Shermans after the war. They were in surplus and most of them had parts like firing pins removed. That way if Americans got angry they couldn't drive a sherman onto the white house and fire. :D
But this lead to sherman rampages where people would hop in the tank and drive through the main roads of their town, crushing everything in their path. Police could do nothing...until the sherman ran outta gas.
"Balancers are 10 a penny"