My M6600 via PR02X docking station no longer connects to monitors

Hello,

I have a M6600 which I purchased back around 2012, new. Later I purchased a PR02X docking station and two Dell P2412H monitors, all new. I set these up and they worked fine for years. About four years ago I connected the monitors via a switch so I could switch between laptops without unplugging and plugging cables. This switch worked fine. I later added an mSATA card to the M6600 and installed Windows 10 on it. I did this to preserve Windows 7 and the many application I have installed. Most apps will not work with Windows 10 and would be costly to upgrade. I can now can switch between Win 7 and Win 10 at power up.

Anyway, about two months ago one of my monitors would not activate when I powering up the M6600. After checking the cable connections, etc. I eventually disconnected the montior cables and connected them direcly to the docking station. This resulted in both monitors not becoming active when powering up the laptop. I changed the cable on one monitor from DisplayPort to HDMI so I could plug it directly to the laptop. This works, but this leaves me with one monitor. Not what I want or had.

Can someone explain why this has happended and what I can do to resolve this, that is to bring it back to my original configuration, using both monitors via the docking station?

I have checked the setting but the laptop does not see the monitors, nor do the monitors become active, the orange LED (power) turning to blue (when receiving a signal from the laptop).

Thank you for any help you can provide.

By the way, I purchased a used M6600 and after installing an SSD (had no drive) and Windows 7 and drivers, I tride this laptop. I'm still experincing the same problem. I also purchased a replacement docking station, same model, but no change.