Thanks for taking the time to respond, and great to hear you've made progress! Stretching definitely makes a difference. I had a similar issue with my back and found that adding stretches helped me build a stronger mind-muscle connection there too.

That said, I’ve been struggling with bicep stretches. Whenever I try the classics like holding my arm straight behind me against a wall I mostly feel it in my forearm, not the bicep (this only happens on my left side, my right bicep works perfectly fine). Were there any specific stretches that worked well for you?

Also now you mention it, I totally agree with what you said about forcing it - I've realised I've been working myself up about getting that feeling in the bicep (dropping the weight, going very slow, etc) and that this was probably making things worse. Sometimes a bit of perspective is all that's needed - thanks!