It is possible to modify the holder to use the replaceable type little bulbs. First get the OE bulb out and leave as much of the contact wiring intact as possible. Then with some little imagination, a soldering tool and some fine wire, it's possible to create the contacts necessary to adapt to the disposable bulb. Once you have made the changes, future bulb replacements are easy. The replaceable bulb has 2 wires, one on each side of the glass stem which need to make contact with the power supply, and remain isolated from each other. Since they are normally placed on opposite sides of the glass bulb stem, you need to create two reciprocal contact points inside the OE holder to correspond to those wires on the bulb. If needed, you can solder a little blob of lead onto those bulb wires to enlarge the contact area and ensure good contact inside the holder. Look carefully at the holder and it's construction. There are little holes on the sides which if you use a 1mm drill bit can be enlarged to allow the holder contact wires to pass through and simplify routing them to the positions you require for the disposable bulb. It's a little fiddly being so small, but manageable.