Shifter bushings are worn, hence why jiggling the shifter would cause the lights to go on and off. I presume this is an auto? Anyways, replace the two little bushings on the shift linkage and/or readjust the linkage rods and you should be fine.

As for why only one side comes on and not the other, replace the passenger side bulb with a known good one. Sometimes, the interal wire breakage is at the base - cannot tell by a visual check, but it's dead. If this isn't the case, then check for voltage at the socket contacts.

-- Kane
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Blossom II -'91 745Ti/M46 ... Bubbles -'74 144GL/BW35 ... Buttercup -'86 245GL/AW70
The Wayback Machine -'64 P220/M40 ... The ParaBox -'90 745GL/AW70L