The test to verify if it is the SMC is to lay down on the ground on the left side of the bike and use your foot to spin the rear wheel, while it is turning, your grasp the smc assembly/fork leg and push it forward.
This should cause the rear wheel to lock up firmly. When you release the smc the rear wheel should spin freely again.
Honda dealerships tell everyone that the parts are backordered till whenever....I called several distributors and they ALL said they had them in stock. I ordered a spare rebuild kit and had it in 3 days!
I ordered mine from RONAYERS.COM, but BIKEBANDIT, CLAWSON MOTORSPORTS, and several other distributors had them too.
I agree with the prior comments about changing the fluid ONCE a year no matter the mileage. Cheaper to change fluid than have your brakes lock up and throw you off the bike!
I'd also take a small wood or plastic shim, remove the pads, insert the shim, and pump the brakes so the pistons are exposed more, then clean with brake fluid and a toothbrush, then use silglide on the back of the pads, pins and pistons. DO NOT use spray can brake cleaner!!! it will cause the seals and orings to swell and make the dang things stick!
when you remove the pads check them for WEDGED shape wear! Another sign something is sticking (piston) may not be coming all the way out causing brakes to drag!
And lastly, GENTLY take your fingertips and pinch the rubber boot on the smc and pull it forward. It will pop out of the little groove that it rests in. You can then see the shaft's condition. Rudesters unit had pond scum ooze out of it! It was completely filled with water and muck!
Be sure you fill the rubber boot up on the new replacement unit with silicone grease to keep the water out!
PM me if you have any other questions.
Igofar