Your Grace,
Your Singer 127 does not have any oil reservoir, just a lot of oil holes, many behind the faceplate and under the bed. Feel free to turn the stitch length knob from end to end. It will take 6 or 8 complete turns. Turning CW makes the stitch longer I just finished a full size kaleidoscope/maltese cross quilt, all blocks were completely sewn on my 127 treadle. The upper tension couldn't be more simple, just a nut pressing a spring which squeezed the two tension disks together.
John in WI