I thought about the snake... the plumbing in my house was done by M. C. Escher, and has too many bends than is necessary, and probably travels about 40' before it even leaves the house
must have been an elbow sale at the hardware store that day. I ended up 'red-necking' up a fitting to attach directly to an air compressor. I'll start with a low pressure and dial it up until the blockage is gone... or until I have shards of ABS all over my basement.
I'll keep you posted