Playstation 1 Overclocking SCPH 5501

Has anyone ever overclocked a playstation 1 SCPH 5501 with success? If so how did you do it?

I understand how to perform the overclock, by lifting pin 4 on the cpu then soldering a wire to it and connecting it with pin 6 of the clock chip.

I have done this on SCPH 7001 and SCPH 7501 and SCPH 9001 and the small Psone SCPH 101 small version with success. The overclock was successful.

But on the SCPH 5501 for some reason it just doesn't work. The system will power on and go to the title screen but it is unable to boot games. It can't boot games at 40mhz.

The overclock seems to affect the disc drive, I'm wondering if there is a solution to this. I thought maybe a switch to toggle back and fourth between 33 MHz and 40 MHz but I do not know were to get the original 33 MHz signal on the motherboard so I can toggle between it. Anyone willing to share there thoughts on this.