We use a closet auger with the large 1-3/8" end on it.
Smaller cables can go right by the obstruction and not move it.
This is the plunger we like.
Leave a littel bit of water in the bowl, and use short quick strokes untill the water starts to vibrate,
Then lift up slightly.
Hopefully, it lifts the mass up so it can get another run at it.
You can also pour a five gallon bucket of water into the bowl.