Need Help With Nikon F Shutter Calibration

After quite a bit of study and practice on a parts camera I am coming close to the end of a complete disassembly, cleaning, repair, and lubrication on my good Nikon F. The quality of work is every bit what I'd hoped for. I've managed to lick a particularly stubborn problem concerning shutter speed calbration and am very happy with the accuracy of all speeds but one. The 1/4 second is closer to 1/6. The manual states there is a calibration adjustment point for the 1/4 second speed. But I'll be darned if I can find it using the manual. I can't seem to get my bearings on where part 301 is in the actual camera. Can somebody please take the photo of my actual camera and mark it up as to where this adjustment is? Please no comment on 1/6 being only 50% off. Before I started, 1/4 second was accurate, and didn't stop being accurate until I adjusted the 1/500, which in itself made every other speed including 1/1000 practically dead on the money. That is were 1/4 went up to 1/5.9. If I can find where that 1/4 second adjustment is, all I need to do is tweek it half a hair. Thank you.

I believe I've answered my question through trial and error. One of the youtube videos is incorrect, apparently. While the lengthy video was very helpful in disassembly and lubrication, it seems he has misidenified the 1/4 second setting as the 1/1000 setting. According to the manual from what I can tell, the 1/500 calibration covers 125, 250, and 500 (especially). The 1/60 setting didn't need to be touched.And the 1/1000 is done by bending something after 1/500 has been properly set. Everything is dependent on the worm gear settings at the bottom. In the case of my 1962 F model, setting the worms to 14.5ms is too tight. Mine requires more like 15.75ms. This allowed my 1/4 sec to end up closer to 1/5, which was as far as I could turn that screw. With this ,1/1000 was more like 1/1125, 500 was about 1/525, 250 was very close. 125,60, 30, and 15 were on the nose. 8 was OK enugh and the slower ones were quite acceptable. he worm gears took about 1/2 of a rotation clockwise from the original 60 year old factory settings. Understandable. The fabric belts had obviously stretched. I'll leave the camera open for the night and come back after noon tomorrow and rotate the SS knob a number of times and re-test. At any rate, all these settings are far better than when I started.