Who has legal ownership of an injection mold tool? The toolmaker or the us the customer? Can we take possession of tool?

We contracted to have constructed to our written specifications an steel injection mold tool by a recommended toolmaker in town. Terms were 3 progressive payments based on milestones. Two payments where made and the final payment has not. The mold has documented defects by not meeting written specifications. Toolmaker claims tool is complete and "works". Tooling will not make parts with pre-specified nylon 66 plastic but will make passable parts using abs plastic not previously specified. Tool had been returned, by our contracted injection machine contractor, to the toolmaker 12 times for "fixes" due to defects. Our product was 6 month past due from delays by toolmaker and we have launched product. Now toolmaker is holding the tool until final payment is received. Toolmaker has damaged our business due to delays and defects yet we have to run parts even though defects remain. Its likely that tool will not meet total units production capacity and we may have to have new tooling made.