Undiscoverable ink leak

[Gonzored]

Hi, I’ve been given the hp designjet 500 to have a bit of a play with having used a plotter previously, it was transported in a van between locations and I’m told that it was tricky getting it into the van ( it’s big and heavy. Bearing all that in mind, it works and works well however it is leaking black ink the location of the leak is by no means obvious (hence my need for help), if it got tipped about a bit during the transportation then its had plenty of time to dry up but the stuff is everywhere! Around the fan, drips occasionally from one corner, it’s basically all around the area of the cartridges and further inside ( I had to take it apart to try and get to the bottom of it, but I’m still none the wiser, has any advice would be great fully received.