Buy a Maui RDM shim and use it on your SDM masts. It cost me 25 dollars today.

Attached my Maui boom with much less tension than normal and for the first time ever - it did not slip once.

I tried previously another RDM shim on a SDM and the boom was still slipping.

Helps to protect your mast too.

there is also an SDM mast protector ... same results