Monomethylation of Amphetamine

[lalalander]

I get consistently low yields in the synthesis of Methylamine HCl. Ni/Zn coupling delivers amphetamine directly from P2P with high yields. Which path would you recommend me to follow for monomethylation?

Al/Hg and formaldehyde is a low-yield method. Maybe paraformaldehyde and NaBH4? Or Zn/formaldehyde?

Thanks.