You should try using triethanolamine in place of the Kodalk or metaborate solution. Triethanolamine (TEA) is available from Photographer's Formulary or Use the same amount of it as you do PMK A solution. That is, for example, 10 ml A + 10 ml TEA + 1000 ml water.

This avoids all the hassle of mixing metaborate and the uncertainty of exactly what Kodalk is. TEA is an organic base that becomes basic when you add it to water.