Feedback for Mackie1975 and anyone else following this conversation:
I ordered three types of LED bulbs from Comet Pinball: 4SMD (stubbing shape, with no "lens") in both Warm White and Blue and also 2SMD Warm White Clear lens. I planned to use the 2SMD's for the glass panel lettering and the 4SMDs for the meters.
But Comet Pinball screwed up this order; they did send both the Warm White and Blue 4SMDs, but instead of 2SMD Warm White they sent Red!
Before returning the entire order I tested the 4SMD bulbs behind the meters. Both the Warm White and Blue bulbs showed strong evidence of "shadowing" in the upper 20% of the meter face. Not too surprising, the 4SMD's lack light diffusing capability. For me, this was a non-starter. The "color" of the warm white was OK, but the Blue was "in-your-face" .... too much Blue.
So I contacted Comet Pinball (no telephone, email only) and arranged to return the first shipment and got it replaced with all the same type bulbs: 2SMD bayonet base, Warm White with FROSTED lenses. Just received these today. Being concerned about another possible wrong item shipped, I installed these behind the meters.
THEY WORKED GREAT!!!
I am leaving on my extended trip soon, so I did not attempt to install any bulbs for the glass panel lettering; this would have necessitated me wrestling with these very heavy amps again. I will try the bulbs behind the glass panel in July. However, I fully expect the Frosted Warm White bulb to work great in this role too. Other than being considerable brighter than the original #1866 incandescent bulbs, the frosted version will provide well diffused light behind the panel and the meters.
Bottom line: I highly recommend these Warm White LEDs with Frosted lenses as an MC2205 "upgrade".