You can request a owner's manual for free at S&W's web site.
it is a Model 39-2 9mm pistol
A fine pistol.
Find a gunshop and ask for help
Ask a gunsmith for help
Smith and Wesson 9mm Model 39-2 Chrome finish.
best let a gunsmith dissemble & clean it
If it is a semi-auto and made after 1957 it will be on the frame. I.E., Model 39 or Model 645-2. If by pistol you mean a revolver, you will have to open the cylinder and look in the recess where the crane/yoke rests.
The smith and Wesson model 39 was introduced to the public in 1955.But in 1949 the U.S. Army used it as a service pistol trials
Your serial number indicates that your Smith and Wesson model 39-2 semi auto pistol was made in the year 1974.
This pistol was made in 2008. I've searched the web and can not find any information on how to dissemble it. I suggest you contact Daisy and see if they can suggest or repair it. See the link below.
Impossible to answer without the serial number. You will have to call S&W.
Recommend you ask a gunsmith for help.