My Spectrum Modern 4-4-0 came with a set of replacement domes.  How do I switch them out?  Do I have to take the whole unit apart to
reach the inside of the boiler?

First off, it is not easy to find the section you allude to on the web site.   After finding the loco diagrams the 0-6-0 Porter is not even listed.
And the two 0-6-0 saddle tank locomotives that are listed do not have bulbs in the headlights, as you said, but the bulbs are located internally and the
light is transferred in a roundabout manner by plastic rods.  Your snotty attitude and unhelpful replies are shameful and a black eye for
Bachmann.

I should have been more specific.  Bachmann makes two 0-6-0 tank locomotives.  My headlight question refers to the Porter model,
not the Spectrum model.   I do not have access to a catalogue or other technical data.  I do not wish to buy one unless the bulbs are in the headlight unit.
Thanks.

Thanks Rich, but it still shows on your reply.

Does the 0-6-0 tank locomotive have a bulb headlight or the older optical type"
 Thanks

I have five Bachmann Spectrum locomotives.  Only two run adequately.  The other three all start and stop frequently.  My track is clean and I have cleaned the wheels.  Other locos run fine but these three are always a problem, a Baldwin Modern 4-4-0, a 4-6-0, and a Shay.   It apparently is an electrical pickup problem.  If I disconnect the tender and the the pins from the locomotive the sound in the tender will work, until you touch the tender or move it.  Sometimes it will start again on its own.  Sometimes you have to jiggle the tender to get the sound working again.   I'm not sure how to solve it.  Any ideas?  Very frustrated and fed up with Bachmann.