need help on dynakit st 35

I'm new to tube amplifiers. I got a dynakit st 35 and that aside from the hum in both channels, the left channel also crackles. I also noticed that the left channel was heating up so fast that I turned off the amp to avoid damages. I also noticed that one of the el 84 tubes on the left side was glowing brighter than the others. There wasn't any leaks from its capacitor.

I will highly appreciate any advice.
Sounds like a # of problems, You probably deduced the need for new tubes, and it sounds like the need for new capacitors. I would also be checking around for cold and loose solder joints. Check the values of all components if you can, after 40 years they almost have a right to not have held their values(I know I haven't). Won't get too expensive as long as the transformers are good, you could do a lot of good bringing it up to speed for less than $150, and a nice little amp when working properly
Check the older threads, the st-70 comes up time and again and there have been numerous posts detailing the various aftermarket restorations/upgrades for the unit. If you're going to start doing internal work you might want to look at all your options.
Sorry, I may have mixed the st-35 with the st-70. I don't know how different the two are and both have kits for the latter. Check around though. Some of the tube places may be able to help.
I totally rebuilt one of these a few years ago, then foolishly sold it (*kicking self*). I replaced ALL of the components and wiring, and had the "superheating" problem you describe. I'm not a tech per se, but it boiled down to breakdown of the signal traces on the board causing it to go nuts. What I ended up doing was to etch and build totally new boards for it, with new tube sockets and everythin'. It ended up with only the chassis, quad cap and transformers as original, and it sounded pretty damn good. For reasons unknown to me, the hum ameliorates with input from a powered-up preamp. Like I said, I'm no tech, but I can read, solder, and listen. I always felt that the performance would totally rock with some type of outboard mega power supply, but never got around to investigating that, before (*kick*) selling it. It's going to be a LOT of work to re-do the amp, but it will be TOTALLY worth it and satisfying when you are done. I actually still have one of the original (crappy) boards lying around somewhere (could be used as a template). Do you have a copy of the manual and assembly instructions? If not, obtain a copy somewhere. Feel free to e-mail me directly if'n ya want. -John
Thanks for your suggestions. I brought back the amplifier to the store where I got it and they agreed to fix it. The problem was that they put the wrong tubes in the amp which was a 12ax7 (i think) instead of the 12dw7 or the equivalent. There was also a cold solder joint. They replaced all the tubes and it is now working perfectly so far since I got it back this afternoon. There was no smoke but I thought at first there was a funny smell of something burning or heating up.

The amp sounded pretty good and I even did not expect the bass to be that well because of some reviews that I've read. I was just using the speakers of a sony micro system.

I'm just wondering whether the amp really gets this hot, that is, the cage especially the area above the tubes get a bit too hot to touch after 10 to 15 minutes of playing.
Do the tubes still get bright red. If so you likley have one or more bad coupling caps. they are usualy black(black cat) and right on the circuit board.
This amp ran extremely hot "when new" and I assume that this is normal now that it is old. If you want still hotter then find an Eico HF81 in good condition. This is not saying that there is nothing wrong with the amp, just that they did run hot when in new and stock form.