I tried to fettle the washer on a tap, but the retaining screw wouldn’t undo despite WD40. Then Mrs Dan wanted a bath, so I put that back together for another day.
I did, however, get the worst of the mud off my bike, give the chain an oil, the rear brake a tighten, and a run over all the bolts to make sure. Then tweaked the saddle, bars and bar bag bracket a little as i was feeling the weight on my hands a little.