This needs a little dissecting:

1) Did you replace what was in the reservoir? Flush through the return hose?

2) Where was the leak? What did you repair or replace?

Seems like the answer to 2 is you switched back to ATF and let it fix itself. Not meaning offence, that’s a strange course of (in)action for a keeper.

In retrospect switching to PS fluid might be why the weeping pitman arm seal of the ‘87 300D wept worse. I replaced that seal and all was well.

Sixto
98 E320s sedan and wagon
02 C320 wagon