What was the two main problems caused by using The vales on the colossus?

The use of valves on the Colossus, a World War II codebreaking machine, led to two main problems: reliability and heat generation. The valves were prone to failure, which could disrupt operations and necessitate frequent repairs, impacting the efficiency of codebreaking efforts. Additionally, the heat produced by the valves could cause overheating, further complicating the machine's operation and necessitating additional cooling measures.