Troubleshooting a Holly meat grinder

[raharra]

Our local butcher shop called today. His 3 phase 240 volt Holly meat grinder was working fine yesterday, now it will not operate.
The grinder has two safety switches (mag switches); the hopper has to be in place and the lid shut in order to complete the control circuit.
The mag switch for the lid was loose to the point of ready to fall out of its bracket. I adjusted it and tried to check continuity across it.
Both mag switches read over 5 Meg-ohms across them when the switch was actuated. I was pretty sure that I corrected the problem by adjusting the lid switch, so I tried the machine and it worked fine.
How do you check a mag switch if it does not have continuity across it? Is there a more effective way to verify a mag switch's operation.
Thanks,
Rick

[crymtide]

Use a magnet you bring with you to flip switch open and closed while ohming.

[raharra]

I used my "furnace fooler" on both mag switches; it did not affect the resistance of either one. I guess that the stainless steel controls the switch where my magnet does not.
Actually, this was a simple problem to troubleshoot and correct. I would like to know how to check these type of switches for the next time when it is not so obvious.
Thanks,
Rick

[crymtide]

If the switches are solid state as in newer Ditto Dean food processors, they have to be activated by the original strike surface and I have found that using jumpers to my meters to see actual power circuit is a way to check the switch. in the Ditto Dean instance disassembly to install jumpers along with reassembly to check the switch is necessary. An easier method is to carry a replacement switch and install it in the circuit. if the switch is bad the unit will now work. Intimate knowledge of the equipment involved will allow you or me to leave this switch as last in the testing procedure so your not changing switches often.