What was found
PDX - FLT 25 - NOSE GEAR UNSAFE LIGHT ILLUMINATED DURING CLIMB AT 20,000 FT VISUAL INSPECTION OF VIEWING PORT REVEALED NOTHING OBVIOUS. LIGHT EXTINGUISHED AT 26,000 FT AND DID NOT RE-ILLUMINATE. INSPECTED NLG PROX SWITCHES CONDITION AND SECURITY CHECK OK. REPLACED PROXIMITY BOX, BITE CHECK OK. OK FOR SERVICE. (M)