I have learned that when I have had what seems to be insurmountable difficulty remembering a thing, there is a point where to keep trying is self defeating. It is then that, when I have decided to give up then at some near - or sometimes not so near - point in the future that whatever it is sometimes comes to me. I have found this not only with regards to pl's but life in general this time.
I think the pressure of repeatedly trying too hard can in itself create a mental block.
If I give up and 'forget' about it then weeks, months or years later remember that I was trying to recollect the full memory of something, and it still hasn't come to me, then I know that it wasn't as important to me as I had thought it to be, because if it had been then it would have 'got through' while my mind was relaxed and not stressed with such efforts to remember.
Also, I have found that concentrating so much trying to remember one thing, or even a few things that are elusively 'there' yet not quite visible, can block me from remembering other things that matter. I mean, if our minds are so full of one thing, it limits space for other things.
This might or might not be what other people experience, so just a thought that what could work best might be to take a rest from trying to recollect things and let your mind work only in the here and now, in everyday life, for a while. Take a breather, a rest, and see if anything transpires when your thoughts are off it and you least expect it