Have experienced this problem many times myself, and here's how I solved the problem each time:
You will need the following items:
A white paraffin candle
Bowl of water
Clean soft cloth or towel.
1. Using the "butt" end of the candle, rub it slowly and repeatedly in a circle following the inner circumference of the head's underside where it meets the wood flesh hoop. Do this while the skin is tucked, intact, and dry. I recommend using the paraffin quite freely. Don't worry about "too much", as it will soften and not be visible when this task if complete.
2. Repeat the paraffin application on the surface edge of the wood bass drum hoop where it will contact the flesh hoop of the calf head beneath it.
3. Then rub the wax in a circle all around the top outer shell circumference of the bass drum, as well as on the bearing edge itself, until wax coats all areas to which the head will be make contact.
4. Then place the counterhoop over the head, place them on the shell, and set all of your claws and T-rods in position hanging down from the hoop.
5. Get a clean cloth, handkerchief, or towel and a bowl of water. Wet the cloth and rub gently in a circle repeatedly starting the at center of the drumhead and working out towards the flesh hoop area. Do not actually moisten the part of the head where it is tucked to the flesh hoop. Repeat and repeat.
6. The head should then begin to relax, at which point you work quickly to align and slightly tension as many rods as will go down into their inserts. It's only necessary to tighten each one by one thread! Just enough so that the claws and rods are inserted and holding.
7. Continue using the moistened cloth as you work with the rods and claws.
8. Sometimes it is actually necessary to SIT ON THE EDGE OF THE BASS DRUM HOOP! - on the side which is not wanting to go down.
9. Eventually, the entire head, thanks to the water relaxing the skin, and with the lubrication of the paraffin, will suddenly "give way" and slide over the shell with a "swoosh" sound.
10. Then quickly realign all claws and rods and evenly tension them.
11. As quickly as you did all the above, the head will immediately begin to re-tighten. You must then stay with the drum and relax all of the T-rods to compensate and relax tension while the moisture in the head evaporates and the skin tightens up.
12. Best to then let the drum set and sit overnight before tensioning as you normally would. You can always slightly dampen the head in the center again to help the head seat and accommodate to the shell and bearing edge.
It's a bit of chore, though not too terrible, and worth all the trouble!
Yes Sir