Replacing bulbs that are out - three steps forward, one step back

FAILURE MODE OF VINTAGE WIRE LEAD INCANDESCENT BULBS

The display panel of the IBM 1130 is similar to those used on the earlier 1401 system as well as the low end models of S/360 such as the model 30. A frosted panel has incandescent bulbs behind it, fitted into a plastic honeycomb that separates and holds the individual lamps. 

IBM uses bulbs with two wires extending out of the glass envelope. They are fitted into nylon holders so that pins can be pressed into the holder's bronze cylinders to make contact. When a bulb burns out, it can be removed from the holder and a replacement inserted. 

However, the point where the wires enter the glass envelope is susceptible to corrosion and failure. As these have aged, many of the wires snap off clean at the glass surface. Often both wires snap off because the corrosion  attacks both equally. 

The Lamp Test function of the 1130 lights all the bulbs, allowing a quick identification of which lights are not working. There were about 20 or 25 that were not working when I checked this morning. Bulbs are mounted onto long thin PCBs that hold up to 16 individual lights. The entire group of up to 16 has to be pulled out of the honeycomb in order to change one lamp. 

When I look at the lamps I removed, most have failed due to the wire breaking off the envelope. For example, here are the few bulbs that are actually burned out, followed by a picture of all the bulbs that failed due to broken wire leads.

Bulbs that won't light

Bulbs whose wires broke off

EACH INTERVENTION TO CHANGE BULBS CAUSES MORE TO BREAK THEIR LEADS

For example, if I pull out a group of 16 to replace two bulbs that were not lighting, when it is put back into the honeycomb some others, previously working, will have failed. Thus, if I attempt to replace every nonworking light position, invariably when I check at the end there will be new dark lamps. 

LONG TERM SOLUTION IS TO REPLACE ALL WITH MY LED BASED BULBS

Only by converting all the bulbs to the LED versions can I stop the failures and keep the display panel fully operational. I am building the new bulbs as fast as I can.

BUILDING LED BULBS INTO NYLON HOLDERS IS A SLOW LABORIOUS PROCESS

Because the leads passing through the bronze cylinders have to be very thin, thinner than the leads of LEDs or resistors, I have to solder 26ga bare wire to the leads of the LED and resistor, making the original lead as short as possible. The original leads and resistor have to fit in a relatively small space inside the nylon holder and the transition to 26ga wire has to be complete before it enters the bronze cylinders. 

I also have to prepare the nylon holders, which invariably have broken off wire from the original failed incandescent bulbs. This wire must be removed first before I can install my LED assembly into the holder. 

I am able to complete about 10 to a dozen LED bulbs per hour. There are a bit under160 lamps in the display panel, thus it will require about 16 hours of time to complete all the replacement bulbs.