slightly OT: replacing ebm papst fan

I've got a piece of equipment where a single ebm-papst fan has failed on a fan tray that contains 8 fans. The manufacturer wants $2500 for a new fan tray. This seems like a waste of money to me and I'd like to fix it myself. The entire equipment refuses to stay powered up with one bad fan. The fan is made by ebm-papst, part number 3214J/2H4F-191, 24V DC, 1.2 amp, 29w. I'm pretty sure it's a "VerioFan" which implies it can be variably controlled for RPMs, and then it has a tach output. These feed back to a motherboard. Is anyone familiar w/ how the signaling works between the PCB and the fan? Maybe PWM? I believe there are 4-pins on one connector (molex style 2x2), and then another 2-pin header which is glued (epoxied) in place. Is it possible to fake out the tach feedback by simply connecting those wires to another working fan? I'm in the process of searching for datasheets, but I believe this model is discontinued. Thanks Keith