Main line jetters work great in my area for heavy roots any mainline machine cannot clear. Yes, there are sewers that will have stronger roots than any commercial mainline cabling machines torque. I enjoy snaking and cutting out the roots a lot better but the tow behind jetter is best for roots...
Yeah, grease does suck.... especially on island style kitchen sinks. Loop vents and no clean outs. The pipe will fill with water and flood the house at a high psi from the jetter
It can be easy.... if your'e in a part of the country where roots are aggressive and invade the line often, they cannot always be cleared. The roots will just bind the cable, even if you use blades. In my area, outside drains are put in by landscapers and they use the cheapest PVC, I've gotten...
Is there any bushes or trees nearby? If so, odds are roots are intruding into the line more often than not. A heavy duty snake 1/2" cable would be required to clear it. If there is no vegetation nearby it could just be debris that have fallen into the line over the years and it would clear by...