By all means start with the simplest possibility - burned out high beam bulb. Don't have a spare? - swap with the known good one.

But if it's OK, then behind that right side headlamp assembly just aft of the radiator bulkhead is the connector for the wires. There will be a Blue (low beam), a Red (high), and a Black (ground)in the plastic sheath. My bet is a bad ground. Locate the point at which that wire is screwed to the inner fender - I think it's below or behind the windshield washer reservoir. Unscrew, sandpaper the little ring terminal and the sheetmetal clean, refasten.

Also disconnect the connector that carries the Red and Blue wires and clean those contacts - or at least plug/unplug it several times and this will self-clean it a little.

If your low-and-high beam bulbs on the driver's side are working there's nothing wrong with your beam switching (aka 'step') relay, as both left and right high beam bulbs' Red wires are fed from a common terminal on that relay. Your problem is downstream, probably the ground.

If this cures things, do the driver's side - it's on the way to being a problem too.
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Bob (son's 81-244GL B21F, dtr's 83-244DL B23F, 'my' 94-944 B230FD; plus grocery-getter Dodge minivan, hobbycar 77 MGB, and a few old motorcycles)