I had a cap go on a old Multiblitz 702 head I bought many years ago,
I paid like $50 for it as it had a broken power output knob. I replaced
the pot fired it up triggered it on low one or two times then triggered it a
full power --BANG-- one of the caps went. I had a hard time finding one
in the end I found one that fitted with the same spec in a junk shop.

The Multiblitz is still going strong afted many years of use.

Older flash heads are alot easyer than new ones to fix....alot less
electronics in them just take care around caps I always discharge them
with a big resistor 10watt (100k)

Just be aware that older flash camera trigger/sinc voltages can be quite HIGH
this voltage will fry a Dslr or AF camera

The best source of cheap replacements is your local flash repair person
they normaly have dead heads they will part out if you are nice.