I bought a brand new Dual Rec in December and I returned mine to the store because I thought the Rectifier tubes weren't glowing (plus my sound was awful (so I put two and two together and thought it was blown tubes - I was wrong)) The small peice of metal in the top of the rec valve is only supposed to glow a tiny amount and through the grill at the front you would barely notice it was on.
I fixed the sound problem - it was a bad lead, oops!