weird buzz

[loctite]

ok so i got an old stal amp from my dad. when playing it'll go from fine to crazy buzz/ominous doomsday noise and back to fine with no warning or physical interaction. i checked on the inside nothing looks burnt the bulbs look fine aswel. the only thing i can see wrong with the inside is loose springs that touch the metal pan in the reverb box. what do you guys think?
greetings
loctite

[52 Bill]

ok so i got an old stal amp from my dad.

Welcome to the place. What is a stal amp?

i checked on the inside nothing looks burnt the bulbs look fine aswel.

Things can look perfect, but may not be right electronically. Please give us a little more information about the amp, like brand, model, features and any links to schematics or photos, and we can give you some information.