sɪ ˈɡɑː(r), guitar ɡɪˈtɑː(r), and divide dɪˈvaɪd that have a syllable-final weak vowel ɪ with no tenser variant.
A particularly interesting candidate minimal pair is dissent vs. descent. The first is morphologically dis + sent (compare as+sent, con+sent), with regular lexical simplification of underlying double s. The prefix dis- is pronounced with ɪ (except in Australian-type accents where the only weak vowel allowed in this environment is schwa).
The second is morphologically de + scent (compare as+cent). It has the regular weak prefix de-, which for the reasons discussed this week I write in the third edition with i.
These entries are based on my supposition that there are people for whom the two words are not homophones.
It is possible, though, that I am wrong in this supposition. Perhaps I ought to test it out in the next preference survey I conduct.
If I am indeed wrong, and they are homophonous for everyone, then clearly I ought to revert to writing bɪˈliːv etc rather than the 3rd-edition biˈliːv. (Perhaps I ought to do that in any case if the proportion of people claiming non-homophony is very small.)
If on the other hand I retain bi-, di-, pri-, ri-, there are certain cases which still need discussion. Those that worry me sometimes are se- and e-. In secure, seduce etc. I give only sɪ- (or sə-). Likewise in event. On the other hand Michael Ashby persuaded me that I ought to transcribe eleven with i-, though there e- is not a prefix.
The pair diffuse (v.) — defuse is interesting. Although I use strong ˌdiː- in the second myself, so that they are not homophones, many other people weaken the de- and not only pronounce the two words identically, dɪˈfjuːz, but get the meanings confused. While traditionally to diffuse is to spread and to defuse is to render (a bomb) safe, you do sometimes come across references to “diffusing” a tense situation. I would write “defusing”.