Apply regular stripper to the grooves with cheap bristle brushes. This stripper can be the old-fashioned full-strength kind or it can be the more eco-consciousness variety. Brush it in the grooves completely in 1-by-1 foot sections or 2-by-2 foot sections. Follow the directions for the time recommended and set a timer.
Immediately when the timer goes off, begin removing the stripper. Cover the paint scraping tool with a rag for deep narrow groves. Use toothbrush bristles or other scrub brushes to remove the stripper and paint. Realize that you may need several sets of brushes to use as the stripper and the scrubbing process can eat up the bristles.
Apply a gel stripper to the areas in the wood floors where paint has not yet been removed. Follow the application directions, set your timer for the removal time, and then remove the gel remover when the timer goes off.
Wipe down the floors and grooves with a rag and clean water or a scrub brush with a damp rag wrapped around the bristles (to protect the floors). Change the rags regularly. Follow the disposal directions for the rags soaked with paint stripper as these can be flammable and toxic.
Repeat using the strippers once or twice more. Then follow the stripper recommendations on cleaning the wood floors completely.
For the remaining stubborn areas, apply heat from a heat gun available at home improvement warehouses. Read the directions and follow the heat setting recommendations for the heat gun and the wood-and-paint combination that you are dealing with. Gently scrape and remove the softened paint out of the grooves using a paint scrapper, toothbrush bristles, or even toothpicks or large sewing needles or pins--use whatever will get in the groove to pull the paint out without damaging the wood floors.
It may be necessary to use stripper-liquid or gel, standard full-strength or environmentally friendly versions-to remove the last bit of residue left in the grooves after the main paint chunks, streaks and drips have been removed by the heat gun. Wipe the away with a rag, you might need to cover a scrapper or another object with the rag to fit in the grooves.