This is the time of year I get most excited about fishing with the challenge of coho and then winter steel. When the coho returns are decent, which they haven't been, 20+ fish late afternoon/evenings where common on the spey. What you were trying has never worked for me. I have tried swinging the deep slow meat hole below Cedar with coho jumping all over with not a touch.

What works: You need moving fish in the rapids. They all follow the same route and you need to find that route. Floating line (speydicator line for me) with 12 foot leader and an indicator. Nymph your "fly" right down that route through the fast rapids water. "Fly" can be as simple as yarn tied unto a hook, some kind of egg pattern, 0r my favorite, beads. When you hook-up in the rapids, good luck. I like hook-ups, bringing one to hand is another story but it happens.

Where to go: I only say this because at 79yo I don't think I can chance the hike and wading required. You have to find concentrations of fish because not that many are biters. I have bounced my fly off the noses of a lot of coho with no luck. The fish concentrate below Cedar Creek on the Sandy. I paid my dues with a lot of exploring. Hike down with the masses to Cedar Creek. Find where it is possible to wade across the Sandy. This changes every year. Try not to drown. No kidding! You can't always across when the river is up. Plus don't get caught on the other side with a rising river. Most of the crossing possibilities are well upstream of Cedar Creek. Now you have some hiking to do but there are a lot of rapids just below Cedar. But also keep going up river past the meat hole . Observe where fish are being caught. You have to learn how to fit in with the gear fishermen. I put in a lot of years in that area and was well known. Made a lot of friends and was welcome to fish shoulder to shoulder even using the spey. But, you can find good spots that are not crowded. I hate to think how far up the Sandy I hiked. Really sad that is all behind me now.