BadCat Hot Cat 30R - Reverb Hiss

Cabicular

I have one of these which I really love but after pulling it out of storage it has developed a very loud hiss when you turn the reverb up. The rest of the amp is glorious
I don't recall it was that bad. 
Anyone any ideas? @ICBM ;

Dominic

Valve ?

StuartMac290

Yeah, sounds like a valve is going 

Cabicular

I'll replace it and see how I go thanks

Cabicular

Just reseated every thing with a spray of servisol and its down to a much more manageable level
Should have done that in the first place !
Thanks for your help folks. Appreciated as always