Sounds like you have a leak that might be getting air in the system causing the spongy breaks. I would try and identify where the leak is coming from first before anything else.
Just wanted to see if anyone was interested; I got frustrated about a month ago when the grinding noise came back after 3 months of rebuilding the ABS motor and decided to buy a used complete unit online. Not sure if that was the best idea, but it’s installed and working. If anyone is interested...