It is possible to rebuild a Sheridan, But it might be better to locate someone who rebuilds them for a living. Today Crosman owns both the Sheridan and Benjamin line of air gun products. I would do a search on the web for air gun repair or contact crosman at this linkhttps://support.crosman.com/hc/en-us/categories/200223634-Owner-s-Manuals-and-Parts-Diagrams.Crosman has most of their OLD parts manuals online at the link above. This should be a start for you.Also check this sight It will help you locate a repair shop.http://www.crosman.com/general/find-a-service-center
The Sheridan Silver streak air rifle was made from 1949 up to the 1990's after that it became the Blue Streak.
It was made in 1975
Here is the link to all of the manuals for Sheridan and Benjamin. Crosman owns Sheridan and Benjamin See the link below.
There are 3 versions of the Sheridan Blue Streak. See the link below for the 2nd version. BTW today Crosman owns the Sheridan and Benjamin line of air guns. This link is from Crosman
The Blue Streak has been in production from 1995 to present. If you want more Information I suggest you contact Crosman who owns both Benjamin and Sheridan. See the link below.
It all depends on age, use, and condition of the rifle. Is it in Poor, Fair, Good, Very good or Excellent condition. Sheridan made 4 different model C series. The C Silver Streak, C9 Silver Streak, CB9 Blue Streak, and C9BP. Which one are you asking about?
Around $100 in good condition.
It was made in 1975. (Today Crosman owns Sheridan.) See the link below and then scroll down to "Sheridan"
If you are looking for a diagram. Crossman (Owns Sheridan) has diagrams on-line on their homepage. See the link below and click on "Download a manual." You will also find the parts diagram on the same page as the owners manual.
The Blue Streak went into production in 1995 and is still produced.
Sheridan made several C series rifles. I assume that you are asking about the C Silver Streak. Not the C9 Sliver Streak. In order to give you an estimate I need to know the condition of the rifle. Does it still work? Does it hold air. What condition is it in? All these determine the current value.
Your rifle was made in 1977. It's one of two models, here is how to determine which one is yours. Measure your rifle barrel Model CB Blue streak barrel is 19.5 inches. Model CB9 Blue streak barrel is 19.38 inches 36.75 overall. It also has a Monte Carlo stock ( cheek rest).