Thank you for your question, Dan.  There are diseases, both bacterial and fungal, that cause this decay to happen.  With this little bit of information, I would guess that it is a brown rot, described here:  https://pnwhandbooks.org/plantdisease/host-disease/maple-acer-macrophyllum-wood-decay

However, a conclusive diagnosis can be done only by examining the tree and the "ooze".  I suggest that you either hire a certified arborist to examine it (https://www.treesaregood.org/findanarborist/findanarborist) or submit plant tissue to the OSU Plant Clinic (https://bpp.oregonstate.edu/how-submit-plant-materials).  Good luck!