Speedometer failing

My 05 ST1300 speedo started failing a month ago, it would work, then die for about a mile then work the rest of the trip. Then the fail time began to rapidly extend. Now the 1st 15 miles of each trip I have no speedometer, it just sits at 0. Then suddenly kicks in and works for the rest of the trip. All other electronics seem to be working fine, the Tach, lights etc. Of course the Odometer stops moving when the speedo isn't moving but works normally when it is registering speed.
The only things I can define is when its cool outside (50f and below) it takes longer to start working, when its over 70f it works quicker, like within 10 miles.
Anybody have any thoughts on where to start looking for the trouble?

https://www.st-owners.com/forums/showthread.php?156485-Intermittent-speedometer-failure-ST1300

https://www.st-owners.com/forums/showthread.php?76490-Another-intermittent-speedometer
post 9 in particular

Oh my that is a good question. I am sure that someone will have the correct answer here but here is where i would start the search. I would tap into the VSS wire off the bike, closest to the speedo head as you can or even at the plug, with a multimeter. Thats a Pink/green wire. Tap between the pink/green wire and the green wire. If you spin the rear wheel by hand you should get a reading of 0-5 volts fluctuating. If that's good then cluster or the connection is poor, but most likely the cluster. if no voltage the I would suspect the Speed sensor has an issue, so check at the Speed sensor pink/green to green wire. If it is the cluster, you would have to replace the PCB most likely.

Speed sensor not a hard thing to change mine started acting up sometimes it worked then it would drop to zero. Changed the speed sensor and its been fine ever since.

Am I correct in guessing that the speed sensor is located on the lower section of the right side of the bike behind an opaque whitish soft plastic flap inside a triangle of frame that is small enough that my fat fingers barely fit into?

It is at the lower right side of the engine I don't recall having any flaps in the way though its a pretty easy change there may be a bit of oil in the old one when it comes out but not much. The hardest part was getting at the bolts.