Older circa 1997 pref-finished floor that has larger than micro-bevel grooves. Dirt has become embedded into the cracks and there is a dark line of dirt in the groove.

What is the best way to clean that dirt out of the groove? I tried using a knife to dig or loosen it, did not seem to help much and one would be at it forever doing every crack. Is there some type of steam cleaner or rotating brush that will get down there and get the dirt out?

My re-finish guy has told me that due to the depth and width of the bevel the bevel will not all be sanded off so the dirt will remain at the bottom of the groove. What is typically done to get the dirt out of the groove?

To refinish a floor with grooves I like to use paint remover that is spread into the grooves with a catsup bottle. Once the finish is softened, a triangle shaped scraper cleans it out easily. Then the floors can be sanded, stained and finished.
If you would like to only dissolve the dirt, there are floor cleaners that have a surfactant which will help lift the dirt without bothering the finish. Hot water will help the chemicals lift the dirt without scrubbing which can dull the surface.
Drying the floor out after rinsing off any residue will be important. Use a room heater or turn the heat up after you finish or you may get some minor cupping from water penetration, so try not to flood the floor.

Thanks for the tips. Can you recommend a floor cleaner ( that I can buy anywhere ) for this task.

A surfisicant sounds like what I am needing. I can scrub it with a brush but it jsut moves the dirt around.

Don't care about the finish. Sanding it once I get it cleaned out. These bevels are very deep, to the poin that they cannot be sanded out so I must get it clean first.

If you are going to strip the finish, use a methylene chloride paint remover.
It will soften any dirt and the existing finish so it all can be easily scraped out.
If you only want to remove the dirt, you can use a hardwood floor cleaner that has a low suds detergent and surfactant like most of the hardwood floor and laminate cleaners contain. Bona, Glitsa, Precision, Duraseal are brands that have a surfactant.

OK, I will try the cleaner and a stiff bristle brush to get down into the grooves. Appears it is going to be a lot of elbow work to get it clean.