TR606 not scanning beyond 5, also no subdivision markers on 1, 5, 9 and 13 when Function button pressed

The TR606 wouldn't progress beyond 1 until I changed the RAM. Now it doesn't go beyond 5 and cycles around. I've gone through the pattern clear process and tried to change the last step but when I press the function button it doesn't display the quarter notes markings like it should. This might be because I removed the RAM to see if the fault was due to the RAM but it doesn't seem to be the case. The video is shot without RAM in the sockets (the new sockets are not shorting BTW, PCB looks good with no obvious cracks or shorts that I can see). Makes me think there is a short around step 5. Where should I check? (as you can see from the video the switches seem to work okay.. I've also checked the diode array for switch 5 and that seems fine too).