Fluctuating Pb level at higher frequencies

[Alex SE]

Was about to adjust RS-BX727 and discovered something strange about it.
Higher frequencies are fluctuating as on picture. Replaced a roller with another one but the problem remains and I just don't have an idea what can be a problem. Anyone seen something like that before?
- Pinch roller replaced
- Head demagnetized and cleaned
- Tested with both professional and a home made tape (recorded on RS-B965 and checked)

00-15sec 400Hz
15-30sec 3kHz
30-38sec 10kHz
Seems that fluctuations are present even at 3kHz but not so obvious as at 10kHz

 

[J!m]

Playback; not lead. Got it.

 

[Vintage 700b]

Pb got me too when I saw it, thought Lead at first too.

 

[J!m]

I’m sure I have fluctuating lead levels in my blood…

 

[Gibsonian]

If I wouldn't have hung out by the window snacking on paint chips there is not telling what I could've accomplished!

 

[J!m]

Sweet AND crunchy!