4pin DIN ac/dc power supply pin-out for the RM40?

I have recently acquired a Mettler Toledo RM40 Liquiphysics Excellence Refractometer, which is obsolete and therefore no longer supported by Mettler Toledo. Unfortunately, it was missing the ac/ 24V dc power adapter. I purchased an adapter with a 4pin DIN connector that *claimed* to be compatible with the RM40. However it does not work. When I measure the voltages on the ac/dc adapter, the top two pins (the ones near the key, spaced slightly more apart from each other) are at 24V, and the bottom two pins are at GND. However I have also measured the resistance between the contacts on the corresponding receptacle on the RM40, and my ac/dc adapter would create a short-circuit if it was plugged in. The RM40 manual does not appear to have a pin-out for their power socket and so I'm hoping somebody on this forum either knows what the pin-out is, or is willing to measure it for me, or has a Mettler-Toledo ac/dc power supply for the RM40 that I can buy.

Equipment: Mettler Toledo RM40 Liquiphysics Excellence Refractometer