[sdiy] TR-606 stuck on one step patterns?

[Tom Bugs]

I wondered if anyone could suggest any pointers for this TR-606 trouble:

I got the machine in busted state a good few years ago - the back of the 
case / battery box a bit broken up and with small damage to the PCB 
corner near the power entry. After a few resurrection attempts I got it 
working again and it has been happy for a few years. I've not used it 
now for a few months, but when I came back to it again it has developed 
a problem - Run/Stop works fine, as does pattern select and the drum 
voices, but all patterns are stuck to 1-step lengths. The Function 
button (SW7 on the switch sub-board) does appear to be good, but I'm a 
bit stumped from there.

If anyone has any pointers or experience with such a problem it'd be 
great to know. Dead CMOS? Dead central CPU? Electro cap problems?

Thanks in advance for any help possible.
Tom