Smoke coming out from capacitor- UK crack- pics attached

[Kyle 491]

1st time powering it up, was Ok for a few mins while testing voltages then the capacitor at terminal 20 and 21 start smoking. The 240V power supply leaking brownish fluid or maybe just the white plastic label on it melting; it feels crunchy to the touch when I push down on that area. The bell end got extremely hot extremely quickly. Any ideas what I did wrong/what the problem is?

Btw I used a power extension cable to connect it to a plug socket, probably a bad idea, wondering if this had any effect.

Will try to upload pictures later, connection is being interrupted on the site whenever trying to upload a photo :/

Thanks for your help.

Edit- Capacitors orientated the right way. I just noticed rings of solder around terminals 4 and 5 of the power transformer that were present on delivery but I stupidly ignored :/ Could this be to blame? Pics attached.

[Doc B.]

It sounds like the power trans is now shot. Possibly that capacitor was installed backwards or a hot wire was accidentally miswired to a ground connection.

[Paul Birkeland]

I'm a little nervous about the UF4007 diodes and they way they are built into the amp.  It would appear that you may have a short between 20 and 21.  Have a look at page 27 in the manual to see what I'm speaking of, the clearance is pretty critical.