[murphyv310]

Hi.
Where has the radio been used? One fairly common issue is when it's used in a damp or steamy environment. This can effect valve bases and paxolin boards, it's a somewhat gradual issue and can take time to be noticed. The boards absorb moisture and become very slightly conductive as can valve bases, even the plastic variety believe it or not, had this issue at various times over the last 52+ years.