Troubleshoot OB-8 arpeggiator (adding notes)

[WhinyLittleRunt]

The arpeggiator on my OB-8 has suddenly started adding an extra note in the sequence after my voice boards were repaired for 2 voices that couldn't tune (switch chips replaced); it seems pretty consistent, like it's the next note up from the bottom note played that is triggering. I double checked the service manual to see if there was a calibration procedure for the arp but there isn't. I'm not sure how the arpeggiator would have been affected by the repair of the 2 voices since I thought it was controlled by the microprocessor... either way, where should I start troubleshooting? I know you're all going to say take it back in but the repair was done by a reputable local tech/acquaintence whom I know pretty well and was done as a favor, so I'd like to see if there's anything I can isolate first before dragging it back out to him since the main issue was fixed.