Penultimate if no heavy syllables, else leftmost heavy syllable. It is common for affixes to not affect stress, regardless of syllable-weight in the affix.

the stress falls on the penultimate syllable unless the vowel of the penultimate syllable is the reduced vowel /ɨ/.

when the vowel of the penultimate syllable is the reduced vowel /ɨ/, the stress falls on the antepenultimate syllable, in disyllabic words where the first syllable of the word is the reduced vowel /ɨ/, the stress falls on the last syllable.

Stress can fall no further left than the antepenult. "Default" stress falls on the ultima if the word ends in a consonant (except for a class of verbs ending in -EN) and the penult if the word ends in a vowel, but the addition of suffixes may require stress to move in order not to fall before the antepenult (e.g., KARÂNY "see" —> KARĀNYÉSHEZĪ "used to see [pl.]").