probe head grinding gears!!

If you have to replace it then get the same exact head. There are enough physical differences between Renishaw and Hexagon probe heads to cause problems in parts with low clearance.

MSC has them in stock. I would advise not to buy a used one. You can install it yourself but I would also advise that you pay for a trained technician to install and recertify the machine.

1) RBE (return by exchange) to Renishaw.

2) Go to someone third party that does repairs. I've done this with a PH9, since it isn't supported anymore. This wouldn't be my first choice. There would need to be some serious extenuating circumstances (time or money, not like being cheap, but like the money just doesn't exist and won't exist to go to Renishaw. Of course lack of money takes out option 3 below).

3) Pay Hexagon to make any changes required to the machine and wiring, along with controller differences for the head and potentially probe, and switch to a Tesa head, as stated, lots of physical differences that can make lots of programs stop working and/or crash.

4) Pay Hexagon to change the head for you with a replacement PH10. I've taken heads on and off machines enough that I wouldn't do this, as I assume I'm paying for option 1 plus Hexagon's field service. But if you have no experience and fear of doing damage (that might be a self fulfilling prophecy), this is on the table.

I'd personally go for the RBE to Renishaw. Provided they have one in stock.

Do the Rebuild By Exchange, provided the controller is still compatible. Not very difficult to swap heads just make sure to "Square up head to machine axis"

HTH

One more vote for Repair by Exchange. Renishaw tests the heck out of those RBE units before they send them out. They are like new. If you pay an extra fee, they will send it out right away, before receiving the broken unit.

And, as Tater said. Not very difficult to install.

something...

We just replaced the PH10MQ on our Global 9.15.8.
The PH10MQ is no longer available. PH10MQ Plus is the replacement.
Requires a new controller.

Renishaw sells a kit that makes swapping it out a piece of cake.
Biggest challenge is getting the DIP switches correct.
Renishaw put one of the DIP switch boards upside down in the new controller.
If one doesn't overthink it and simply follows directions, it works as advertised.

Even with the new controller, It was still cheaper to replace than the TesaStar-M on our 5.7.5.

RBE "advanced replacement" the old probe head with Renishaw. it's quick and easy.
1: turn entire machine off
2: remove probe sensor and adapter
3: unscrew the 4x screws holding probe head into z axis quill
4: gently pull head down (you might need to twist the head while pulling wires down as the Hexagon FSE's often have to shove a bunch of extra wire up the z quill and spin them in the process.
5: unscrew the connector(s)

repeat in opposite order to put back on. Again Make sure machine is entirely shut down.
ooh and when screwing the 4x screws back on, gingerly thread them in to make sure you don't cross-thread those 4x holes. Don't over torque them, either. they are aluminum female threads and a steel screw. you will cross-thread and/or strip the z quill if you don't take your time on this step.

Before completely tightening the head down, push one side of head to be firmly "datumed" against one side of the Z axis quill's inner walls. that's all you really need to do to square the head to the machine.

turn machine on, calibrate master probe, and recalibrate all probes and angles.
done.