Problem with Eater SAP-1 computer

I am having a problem with my Ben Eater SAP-1 breadboard computer. As shown in the video, the 74LS157 source selector chip used to switch the RAM write source from the manual write switch to the clock-driven RI signal creates spurious Low pulses into the RAM write pins when switch between program and run mode, causing the RAM to be overwritten. Any advice on how to resolve this would be appreciated.

Видео Problem with Eater SAP-1 computer канала Michael Kamprath