You need to find a gunsmith.
The Legacy / Puma 92 is one of them! http://www.gunblast.com/Paco_Legacy_454.htm
Rossi produces the Puma which is a .357/.38 lever action rifle . It is a copy of a Winchester 92 I think. Also marlin, and maybe even Henry have .357/.38 levers.
Best left to a gunsmith
Marlin, Henry, Puma
marauder.homestead.com
Best left to a trained gunsmith
You really should leave this to a trained gunsmith.
.38 Super MAY be fired in a .357 magnum firearm. Due to the semi-rimmed cartridge case, it may not extract, headspacing may be off. Not recommended.
IT Has 1 you can disassemble the cowl lever & wiper motor to get to it.
You will have to contact Rossi or find one of their catalogs
You can download a manual here - http://www.henryrepeating.com/freestuff.cfm
left side front of trigger is a lever. pull down on lever and the side plate will come out. slide barrel forward and your gun is apart