I'd like to see Canada raise the following issues when NAFTA is renegotiated:
1) The US provides billions in subsidies to its agricultural sector.
2) Buy American policies
3) US laws that prohibit the export of raw materials.
4) US laws that prevent foreigners from bidding on ship building  contracts.
5) The dispute resolution mechanism is weak. It needs to be beefed up and sped up. No more years and years of litigation. It should come to conclusion within 6 to 12 months.
6) End the silly practice of the US coming to a 'preliminary' ruling on countervailing duties that cannot be appealed. Only the final ruling can be appealed and that can arrive 12 months later. Meanwhile the supposedly guilty company(s) has to pay the duties. Either eliminate the preliminary ruling, or keep it but no duties come into effect until the final ruling has been made.