[Collins] 75A4...Name the type set screws holding dial drum to shaft

[John King via Collins]

I need to remove the dial drum from my 75A4 and can't tell whether the set screws holding the drum on the shaft are Bristol spline set screws or Allen head screws? I don't want to strip out the screws ruin them. I cannot see well enough to determine the correct tool to loosen the two set screws holding the dial drum to the shaft. I am in the process of replacing the dial drum overlay.

If someone knows for sure whether Bristol or Allen tool is the correct on for this application, PLEASE share that information to me. I am well aware that folks sometimes ruing Collins knobs by failing to use the correct tool for the job. Thanks and 73, John, K5PGW