In order to repair the Blue Tooth an external antenna must be attached to the Mac Pro. You will need a suitable antenna and cable.

TL-ANT2408CL 2.4 GHz Indoor Omni-Directional Antenna

U.FL Mini PCI zu RP-SMA Pigtail Antenne WiFi Kabel 20 cm length

The antenna will be attached to a PCIe slot cover. To make a hold in the correct position, first punch a notch at the place where you want to drill. Then drill with a 3cmm metal drill, then with a 6cmm drill. Use the slowest speed setting on your drill to get a well shaped round hole.

After drilling the hole, file away the rough edges of the hole. This same technique can be employed when tidying-up the hole in the CPU tray.

Assemble the antenna cable to the PCIe slot cover.