The Load Regulator on the SD60 has to be in Full Maximum Field to make the proper HP. The excitation system is designed for the load regulator to operate there because it establishes the KW Ref. The KW Ref that you want to see in notch 8 is 2686. Take 2686 and add three zero's to it 2686000 and divide by 700 and you should be making 3838 Horsepower. When the load regulator backs out on these units, it will weaken the KW Ref and of course you will not make the horsepower you are wanting to see. From my experience over the years, I have had several SD60 units have the Load Regulator back out in notch 6. With this exception for notch 6, all other notches will remain in full maximum field at 100%. I am sure that you know that when you put the SD60 in notch 8, sometimes it may take 5 minutes or so to reach full horsepower and this is normal. Fuel Pressure on a SD60 should be around 55 psi +/- a little. On the SD60 they have a Spring Loaded Fuel Drain Relief Valve on the Fireman Side down low between the Fuel Pump and the Air Compressor. Sometimes when a SD60 has been serviced, people forget to release the fuel drain valve back to its normally closed position. The Fuel Pump on the SD60 should be atleast a 7 gallon pump. The Governor Quad should be running at .82 on these units with 904 Engine RPM's. Rule of thumb, when your load regulator is backing out, it is mostly a mechanical problem. Take a heat gun and shoot your stack temperatures for each power assembley and make sure that you do not have a cold stack. If you have a cold stack, you might have a bad injector. Always make sure that your exhaust valve bridges are not too tight. They should have a 1/16 inch of clearence if I remember correctly. With the unit in idle, open each Power Assembley Test Cock one at a time and listen for the sound. They should all sound about the same. If one is noticabley different, you might have a exhaust valve that is set too tight. You could also be about to drop an exhaust valve also. Always remember to check your Racks. You will need a Rack Jack and a tool to set them. Dial your Governor Quad in on 1 inch with the rack jack and with your adjusting tool check each rack to be set at 1 inch. To adjust the rack you will need a 7/8 wrench to break loose the jam nut. Other things you can do is, with the unit idling, you can pop test the PA by removing the pin out of the monkey tail and push the metering rod in all the wall and listen to the sound of the PA. They should all sound the same.