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If oil is foamy, that is a good indication it is sucking air.
This can happen if the strainer is plugged.
Did you change the filter and check the strainer?
Did you cut open the old filter and check for debris? Did you find anything?
Are you using 30W transmission oil?
Did you install seals at the strainer?
Are you checking the oil level with the engine running?
Please post the full machine serial number with your reply.