well anyway i have a 76 300d. of course the vac locks dont work, want to get working at some point, butttt i have a question

i was under the assumption that none of the locks work. welll today when i unlocked my drivers door, i just happened to look back, and slowly but surely, both back locks came up (about 30 secs) however, the passenger front lock doesnt move (very had to pull and push down. weirdest thing though went to lock the drivers door, and wouldnt budge, then i figured id lock the back-- well same thing woudlnt budge, after working with the back right lock, it finally went back down, and then the others went down as well.

what the heck is going on here? help plz.

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76 300D 108,110 miles
99 Saturn sl1 80,000 miles - moms
91 Grand Marquis 45,000 miles - Grandparents
97 Ford F150 - 16,000 miles - Grandparents
73 Ford Monarch (parked 65,000 miles - Grandparents