This isn't a technician's site but a Life Hack to explore alternatives. In general, you can't expect any mower to cut grass that is thicker, taller, or wetter than it can usually manage. I would avoid any treatment to the belt not mentioned in the operation manual, in case you make the belt slippage worse. Just make sure the belt is at the right tension.
I remembered that baseball players sometimes use rosin in their gloves to keep the baseball from slipping out.
"Rosin, also known as colophony, is the sap or sticky substance that comes from pine and spruce trees.
Its stickiness lends itself to being used in a wide range of products."
So I went over to a grove of pine trees,...
My other answer approaches the problem from a digital point of view, but you might not have a monitor that accepts audio or a desire to run two laptops at the same time, one being a client of the other.
If you're not shopping for a new monitor/don't have the opportunity to add audio to your monitor and are interested in a low energy solution then the ...
In the case of a phone plus laptop, I'm not sure what you gain; you take your phone with you so when you sit at the location you keep your headphones, you have to plug the splitter device into the phone and then also switch it to the socket that the phone is connected to, which is about as much effort as just plugging the headphones straight into the phone
If you want to be able to listen to audio from the both laptops at the same time, there is no simple or easy hack - and especially not safe, it can even damage the electronics in the laptops.
The safe way would be:
Buy an external USB sound card - mandatory with a line-in connector.
Connect and install the USB sound card to laptop 2.
Connect (with a proper ...