Entry Sensors Not Sticking - Falling Off

Shiherlis (not a SS employee) recommends cleaning with rubbing alcohol and letting dry before applying.

When I (also not a SS employee) installed, I left the sensors off the first few hours (just the face plate attached). My 1st SS3 sensor (motion) fell after being stuck for ~18 months.

One thing to note is that the SS3 double sticky tape isn't 3M command strip brand. It is some knock-off brand which has not rated as well as the command strips that shipped with SS2.

For where you are now, I would recommend you clean the area well and use new double stick tape tape purchased from any hardware or big box store. If you cannot get to it all at one time, start with any that have already fallen or are loose, then move on to the others.

It's a pain, but at this point, prioritize getting your system up and going.

Yes, I recommend the use of rubbing alcohol (and allowing it to dry) to clean the surface before application.

However, unfortunately, I too have now had a Motion Sensor fall twice last week after 17 months (all other Sensors and Keypad remain in place). Fortunately, I was home, and have that particular Motion Sensor set to arm only in Away. I, like, WS729, attribute it to the adhesive tape SimpliSafe supplied with SS3. I never experienced one Sensor fall over 4-5 years when I had SS2. I can presume it was because the old systems used to ship with Command Strips by 3M. The only way I was aware of the switch was because my SS3 Keypad kept sliding upon installation, as well as the same Motion Sensor which fell soon after the upgrade. I knew something was different. When I did not see the 3M logo, I did a bit of research and found the new strips to come from an Australian company I had never heard of - "Removables" by Hookz.

I am currently waiting on Amazon to deliver 3M Command Strips before I very reluctantly go the screw route, as I hate screws and nails going into my walls. But it appears, after seven years and many purchases without issue at my new home, Amazon suddenly cannot locate my residence, and the delivery is experiencing a delay with no timetable for redelivery. If they do not arrive tonight, I will be heading to Lowe's or Home Depot.

I am confident the Command Strips will resolve the problem.

Thanks for your responses.  What a bother needing to reinstall with different adhesives!  I just did a search for 3M command strips and found out that many reviews are also complaining that they are not as sticky as they used to be in the past.  Still, I will give them a try along with the isopropyl alcohol idea.  I also just read that the command strips work better when the area is first cleaned with a Magic Eraser.  So, it looks like I have more work to do!  Again, thank you for the quick recommendations!

Surface prep is important regardless of the brand of strip...must be clean and dry at a bare minimum.

Also, press hard for 30 seconds after attaching the item to the surface.  This seems to help adhesion.