Above having dealer accounts with most manufacturers, I have daily if not more than daily orders for repair parts I
send to McMaster Carr.
www.mcmaster.com
They won't have lenses (but could probably get them) but will have the nuts and bolts solutions others cannot match. Graniger and others can also special order them. Much less a theater supply will have similar vendor accounts and both
stock and can get parts in a similar way.
Hub from another posting will have antique parts and advice otherwise for stuff the manufacturers don't have. But also the manufacturers will more frequently than not
stock even discontinued parts. You can still get
incandescent lamp caps for the 360 series of radial
fixture from them for instance. Either direct
thru Altman or
thru a dealer. They don't sell the casting any longer but even in this
fixture, most other parts are standardized with the
360Q.
Dependant upon the era of
fixture also, what seems similar in photo will be similar in parts. Major lighting for instance while out of business now and absorbed along with others by
Hub, made most of the reflectors in use by other companies. Kupp made the lenses and they were during those days also standardized amomgst brands. The lenses in a 6x9
Altman are most likely the same as that in a Century
Strand. There are some companies such as Edmund that specialize in and can still get lenses if otherwise not available also.
Start on the website and get both part number and description of the part. Than look around for the same parts if not just order those once you present the part number. Having a exploded pictoral file with part numbers of all the fixtures in your inventory is very useful in something you can
point to.
Beyond this, many companies years since they went all
ETC such as us will still have boxes upon boxes full of
360Q parts and especially extra lenses and
lens trains. Such parts by way of a production company might not be advertised, but upon E-Mail to them especially the larger lighting companies, inquiring if they have any parts still in
stock might prove cheaper parts than even E-Bay and other used gear websites might save you in parts.