i have change to use only round tips and no diamant - round works better, the same with the rubbers -i notice 2 rubbers with 2cm diameter works better -is the rubber to soft its splitting ,its to hard its splitting too. On the old sidewinder i do a o-ring on the nipple and the grommet after the o-ring. So the needle is more forward and i use only medium soft grommets. All this helps to get a nice soft splitting free line

I notice that every sidewinder works best on a other stroke - my old one on 4mm ...my newer on 3,4mm. Is the stroke to big you get trouble or you change the volts -the same when its to small.
But i think you need a other setup for yours. Use medium soft grommets , 2 soft rubberbands and round tips - you will see that helps and try different volts. My old is running best on 7,4v and my others between 5 and 6volts.
With the sidewinder you have only to touch the skin with the needle - use only single pass ,i notice its blows most when i use a second pass -or i change to a softer machine or set the sidewinder softer for the second pass.