My 12.5 briggs engine is approx 12-15 yr old. Runs fine when started but won't re-start after shut-off due to too much compression. I need to know where the compression release adjustment (internal I presume) is located and how to adjust it. I have had the solonoid checked & no problem there and the battery is new. Actually, it starts OK with just a little boost from a charger but I obviously don't want to have to rely on that method.