Shure P2R body packs keep shutting off on their own in middle of show. Have to turn switch off and then back on to get them working again. Very tedious during a performance.

Tom is probably right, the carbon contact on the switch wears out. Open the case and replace the switch.
Part #40
Price £ 3.95 + postage if required

bring in your guitar and have the intonation checked on pickups

It's shutting down automatically due to heat peaking. You need to turn off until you are ready to use it.

If you was to turn the deck upside down you will see 4 main screws in the corners holding the silver top to the black chassis of the deck. undo these screws and carefully turn the deck over and lift the top off slowly. I say slowly because before putting it down (you might need someone to hold it for you) you need to un-clip the white plug and there will be a data ribbon stopping you from pulling the lid away. this is the strip you need to check both ends that the connections are clean and pushed in properly (the blue strip on the connector should be facing the middle of the circuit board) be careful not to snap the connector and make sure you push it into its socket straight and not at all at an angle or it could snap. put the white connector back in and pop the lid back on and turn it on to see if worked.

This has the earmarks of battery problem... Supposedly this uses a 9 volt battery... You CANNOT use rechargeable batteries in these as the actual voltage of the rechargeable is lower than alkaline and they will fail quickly and as they age you may get only seconds of operation. When they go off the battery will recover a bit and even look like it comes on again. Do NOT count on the battery LED to give actual answer. When you turn on the unit, read the battery voltage under load with a meter. It should be at least 8.5 volts. NEXT possibility: A chronic problem with body packs is the battery contacts. There is a fine line between having good contact and being able to get batteries out. I have seen where people stuff paper in to increase tension on the contacts.

Sounds like you're over driving them. First check to make sure they're on "line level" not mic. Shutting off is amp(s) in speakers going into "thermal shutdown" IE: overheating. According to your description level settings look good - check to make sure speakers are on LINE LEVEL

I have also experienced differing volumes when using different brands of headphones (I have worked as a sound engineer part time in the past.) It's usually due to a difference in impedance between the different speakers using in the headphones (sometimes the impedance will be indicated on the headphones like 16 ohms.) If the two different kinds of headphones have differing impedances, the apparent volumes at the same level settings will be different

I'd suggest sending the receiver to Shure for repairs.

Replace the batteries and get an AC adapter for it! These do NOT work when voltage os too low.

You will have to recalibrate your pedal. If you don't have your manual anymore try going to www.digitech.com. The procedure for the RP350 so that you don't lose your presets is : 1. Press and hold the UP/DOWN Footswitches until PDLCAL appears in the display (BYPASS,TUNER and EXIT will be displayed before PDLCAL is accessed after about 5 seconds). 2. When the display prompts you with TOEDN, rock the EXPESSION PEDAL forward (toe down) and press either FOOTSWITCH.
3. When the Display prompts you with TOE UP, rock the EXPRESSION PEDAL back (toe up ) and press either FOOTSWITCH.
4. The Display now prompts you to calibrate the V-Switch sensitivity (VSWxxx), where xxx is the current V-switch threshold. Rock the EXPRESSION PEDAL forward and press firmly on the toe once to turn the V-switch on (WAH ON) and again to turn the V-switch off (WAH OFF).
5. If the V-switch is too sensitive, press the right UP FOOTSWITCH to raise the threshold (range is 0-2000. Keep testing the V-switch sensitivity and adjust the threshold until it only engages when you want it to ( too sensitive a setting will lead to the V-switch falsely triggering on or off when using the Expression Pedal).
6.When the V-switch sensitivity is set to your satisfaction, press both UP/DOWN FOOTSWITCHES simultaneously to exit. NOTE: IF the DISPLAY shows ERROR, an error has occurred and steps 2 through 5 should be repeated. Sorry fo the caps but thats how the instructions appear in my sons manual. You can also dowload the manual and an editor librarian (for the 350 at least) at their site. They might even have an update for your pedal. Hope this helps. Keep playing.