Well, mine stock had 3dB anywhere from 400kHz to 1Mhz depending on the vertical scale selection.
After patching up the front end the 3dB is now shy of 11Mhz for vertical scale settings. I implemented similar to bielec’s solution (almost the same). The parts I used are low drift resistors (25ppm 0603) and NP0 0603 capacitors.