Stafford's cyclicity conjecture for torsion Weyl-algebra modules

Let $A_n$ be the $n$th Weyl algebra, and let a finitely generated $A_n$-module be torsion when it has rank zero. A module is cyclic if it is generated by one element. Stafford's conjecture. Every finitely generated torsion $A_n$-module is cyclic. This strengthens the preceding result that every finitely generated torsion module can be generated by two elements; its status is stated as open.