After many years of sitting idle, the batteries became corroded and inoperable. Removed the old pack by popping the top on the HX-20 and removing battery cover plate. Unsoldered and put aside the old wiring harness for later use.
They were in pretty sad shape. Found suitable replacements at Fry's. Tenergy 2200mAh NiCd (with tabs) - they came in a pack of 6.
Connected the tabs in series, and shrink wrapped them together. FAIL! would not fit in compartment. <Sigh>