Hey Bradley,
wood dust on the pcb or overheating can make this. The solution would be sufficient dust extraction, enclosing the controller in an enclosure with a big fan and a HEPA filter, and replacing the noisy small fan by a 120 mm fan in the top of the case. If the system freezes it is certainly the smaller upper pcb which is the Raspberry Pi. I don’t think it is much ventilated should the environment be hot.
Should wood dust be the cause, I would use a ESD-safe brush to try to clean the pcb. Or you remove the pcbs and use CRC KONTAKT LS to clean them.
Also if you had a problem with the SD card, I would not overwrite the old one but buy one of good quality (Sandisk brand).