you can also get some noalox and a just a teeny dab will do ya, this lubricates the threads and you won't booger em up as bad
Also when you take a topper out, run some paper towel down in it to clean out the goo, it attracts dirt and dirt + juice = grinding material = eaten up threads
Once the threads are stripped...well...time to dump it in the "spare parts" box
Found this while looking for the head
eVic Flat Top cap | Cool Vape
Found this
EVIC Thread Repair | ALL ABOUT E-CIGARETTES UK