Rotary buffers are notorious for leaving swirl marks. It's hell when you have to stain a floor and after you've painstakingly sanded and removed all edger marks, you stain it only to find swirl marks. I"m ready to change machines.

Any input on the Lagler Trio? I'd heard this machine vibrates and oscillates which can help to eliminate swirl marks left by a simple rotary buffer. I've heard the square buffers can also leave marks so I'm hesitant to buy that.

I use a Clarke OBS and love it it's slow but if you use the right pad J-hooks are not an issue. 3-m makes a good one

What grit are you using? I use 100 grit screens on my OBS clark 16, vac, and square buff with a 100 screen. leaves my floors flawless. but takes time!

Faint swirl from a regular rotary buffer/sander is normal. It can be minimized by clocking the buffer so the typical 2 oclock sanding spot is going with the grain of the flooring. On dark stains, you will probably still get some minimal swirl. Consider stepping up a grit to 120 screens. Or not screening a stained floor at all. For light to medium colored floors, I find the swirl is negligible and barely noticed. And on darker colored stains, just finish sand with your big machine with 100 and don't screen at all. Screening was developed to blend the edges and the field together. If one details the edges properly by handsanding, then screening is not needed, IMO, on darker stained floors. Water popping the grain can also reduce swirl from the buffer and allow the wood to absorb more stain. Square buffing is optimal but as you already know, it is time consumming.

I'm finishing with a 80 paper leaves them dang nice and still stains real good. It's a rarity that I have to water pop a floor. For awhile I was 120 screening but didn't like how it tightened up th wood and it didn't take stain quite as well. The OBS is slow but it does do good. I'm actually having a Rotary buffer demoed too me in a couple of weeks that I'm lookin forward too seeing.