Damper felts, especially the split wedges, need trimming after some years of use. Typically, these Yamaha split wedges had become so long, they still hung between the strings (dampening them) when lifted by key or pedal. Further more (also especially typical of the split wedges) these dampers had settled lower & lower into the strings and were picking up too soon on the key (ie making the half blow too early), thus increasing the touch weight.

(So, as I was going to have to adjust them to pick up later, they were going to be lifted even less free of the strings, thus worsening the problem: there was no choice but to trim these felts).

If you look closely, you’ll see that the felts to the right have been trimmed, whilst the ones to the left are showing their typical badly increased length.

In the pic with the scissors, the top damper is the trimmed one; In the pic with my iPhone, the damper to the left is the trimmed one: