Unless the speaker surround is showing visible tears, more likely the power amp is clipping due to sagging power supply voltage. Replacing electrolytic caps C702a and C702b gives one the biggest improvement for the least money, but I replaced 71 e-caps on my H182 for great sound and full performing features. If your organ has over 10000 hours you can also have tired 5AR4 rectifier tubes. I have a "professionally maintained" H182 from a church where the hit-and-run technician replaced the rectifier tubes with inferior 5Y4's and a couple of the 6BQ5 treble power amp tubes. I believe he should have replaced C702a and C702b instead, which takes a lot longer.
The best schematic diagram is on keyboardpartner.de, although there is a full service manual rather fuzzy on archive.org. You can read the date on the original cans, usually 66ww for some week of 1966 or like that. If your caps are showing 1992 Manuf date or later or are made by FP or an oriental manufacturer, then these caps might have been replaced already. Then the next ones to do are C703, followed by the sections of the one on the power amp itself.
Read this thread about my take on changing e-caps in tube amps the cheapest and longest lasting way. http://www.diyaudio.com/forums/tubes...ube-amp-3.html FP can caps come from tubesandmore.com or triodeelectronics.com, but have undefined life. Radial lead caps have to be installed on terminal strips from those, but the caps come from newark.com or mouser.com in the US. You can get radial lead caps in life ratings of up to 10000 hours.
You wouldn't believe how striking the sound can be from an H100 if you do 71 e-caps. an A100 doesn't begin to sound like one of these, although torea said his H100 sounded something like an A100 after replacing only these two cap sections.