Those hard to get rare ones ... hmm. It can be a tussle to get them sometimes. Personally, I'd select to downld, if not successful, select from downlds window & press Stop button. Then re-select from search results & press download button. I'd repeat this process backed up with the occasional new search.

Do you have people uploading from you. It generally helps. Also changing the content of your uploads can obtain different sets of users uploading who might just have or be indirectly connected with users who have the file you want.

I see you used the Resume or Find Sources function. These can be effective but not as effective as searches which can bring in fresh results & new people online.