I had a similar problem for my desktop lamp that has the same vendor number (Vendor 173884)and I was able to find a replacement bulb. The bulb that I am using is a Philips 50w. The Ordering Code is: BC50W/T4/12V CAPSULE. The bottom right hand corner of the container says: GY6.35 BASE T4. I guess that is the model number of the bulb. It is a 2000 hour bulb.