T190 Hydraulic Leak- Unknown Source

[Philosaw]

Hi, I have an older non-joystick, foot controlled T190. It has slowly developed a hydraulic leak that I've sort of ignored until now when it's gotten too bad to dismiss. I started by cleaning the undercab and then ran it for a few minutes with the cab up and a flashlight in hand but had no luck seeing anything. I left it until the next day when there was about a quart of fluid under the machine, so I pulled it out of the shop and spent a good hour hot water washing the under-cab until it was as clean as one of these things can be. I then pulled it back in the shop and again ran it without seeing a source though this time I could see the oil coming out of the inspection hole under the hydraulic tank. I looked all around the tank with a light and a mirror and couldn't see anything. Does anyone have any ideas? It looks like pulling the tank would take the removal of about everything...Yikes! Thanks