The US only deck would be an A-4010SU. No multivoltage selector or 50/60 Hz switch. 50Hz line frequency needs a larger capacitor value than when running at 60Hz to maintain the correct phase shift and torque.
The capstan and reel motor run capacitors are multi-value, one for 60Hz, the high value and a supplemental lower value to add to the 60Hz value for 50Hz line frequency. The reel motors can will have four values, two for 60Hz, two for 50Hz. Since you only have noise at high speed and no speed issues, I doubt motor run caps are the issue. The capacitance remains the same for both speeds. Different field windings in the motors are used to change speeds.
With my deck a bad motor run capacitor caused speed issues and the motor itself would hum and get hot, no noise from speakers. I did have a bad Germanium transistor in the preamp circuit that caused a rushing noise. Later decks used silicon transistors.
I'm just a hobbyist with some understanding of electronics. Maybe its something in the high speed eq circuit. What are the first two digits if a five digit deck, or first three of six digit deck? My SU is 64xxx. I can tell by pics that your deck is a later serial.
Is noise same level from each speaker or is one channel louder? And just an FYI, if motor run caps are replaced in a global multi-voltage deck used in US, you can just install the high value and cut/insulate the end of the 50Hz value wire.
FWIW, I uploaded a later 4010S/SL service manual at Tapeheads. I also uploaded a 4010S/SL parts list. There are also some later serial deck transport/preamp schematics uploaded in the parts list post. Early decks will have RA-40 amp, later decks used an AR-40. I tried but cannot upload manuals in the database here. File size too large to attach to this post. I sent message asking if the mods want to add to AK database.
Of interest for SL owners, the parts list contains the missing high bias calibration info for the 4010SL. It's just after the image of the preamp board serial 159808 and after. I wonder if they forgot to add that page to SM as they printed on the front cover under 4010SL “refer to last page” but there is nothing there. No pages have been ripped out of my original manual.
