Those holes were left behind from an early Roland GK-3 MIDI pickup system and don't structurally hurt the guitar at all. There is also another hole on the front of the lower bout from the transmitter. Considering the price the holes are easily overlooked. I had that system on a late 90s Hamer SATF. Much better guitar to MIDI options available now. I have MIDI Guitar 2 and the tracking and accuracy of the plugin is MUCH better, no proprietary gear or cables and even works with wireless transmitters (but you need a DAW like Reaper and USB interface). I can turn any guitar into any one of a hundred synths, even drums.
The knobs are standard notched coarse 18 spline knobs ($10 on Amazon, already ordered).
https://www.amazon.com/dp/B07YWGZL84?ps ... yp_imgToDpIt took my friend a day to decide if he wanted it. I'm surprised it lasted that long. It was at $749 for a long time.