Does your character need armor repaired or fabricated (or upgraded, per my last post)? Well, an armorer is necessary. Will one be available in the next town down the road?
If you don't have a town spec'ed out prior to the characters' arrival, or need some stats to build one out, S. John Ross' Medieval Demographics is a good starting point. Donjon has an automated calculator for ease.
Since this calculator, doesn't have an 'armorer' category, we can use blacksmiths as a surrogate. Based on the demographics stats, not every town (especially smaller burgs) will have a blacksmith. A leatherworker would be better surrogate for a light armorer, but this particular calculator doesn't have that occupation, although the harness-maker could substitute in, as well. Optionally, one can build out populations off Rob Conley's 'Fantasy Demographics' which includes both leatherworkers and metalworkers.
Not every blacksmith will have the skills to repair or fabricate armor.
Is an individual blacksmith sufficient skilled to work on armor (percentage)?
Small (<1000) 65 25 10
Medium (1000-8000) 90 75 50
Large (>8000) 90 85 75
If so - what is their fabricating ability (includes upgrading) for a particular armor type? (percentage, cumulative)
Light Medium Heavy
Small (<1000) 25/70/5 50/45/5 75/20/5
Medium (1000-8000) 20/70/10 35/55/10 40/55/5
Large (>8000) 5/85/15 10/75/15 20/70/10
Coincidentally, Lum over at Built by Gods Long Forgotten posted up his own theory/houserule on OD&D armor a couple of days after my prior post. Take a look.