Most tune up's require a professional air gun smith. This involves polishing the air tube. Trimming or replacing the spring and replacing the trigger. The cost can exceed the original cost of the rifle but in most cases it is worth it.
I suggest you search online for "Air Gun Repair" or see the link below.
which model I, II or III
I am a little confused by your question. Do you mean Webley air rifle. I know that Wembly makes scopes but I am unaware that they make air rifles. If you mean Webley then I need to know the condition and the model of the rifle to give an estimate of value.
50-200 USD
To get an estimate of value you will have to state the condition of the rifle and give the SN#. There are 5 different series of this rifle.
See the link below for a list of places that may be able to help you.
This model was manufactured from the late 40's up to the late 60's. I suggest you contact Webley at the link below for more information.
This model was manufactured from the late 40's up to the late 60's. I suggest you contact Webley at the link below for more information.
The Webley $ Scott Hawk MK2 was made between 1974-77 it had an optional .22 barrel. Please state the condition of the rifle to get an estimate of value. Is it still working? Is it in Poor, Fair, Good, Very good, or Excellent condition?
In poor condition it is worth $30 in Like new condition it is worth $150
100 or so
look herehttp://ukchineseairgunforum.myfreeforum.org/index.php
A Webley & Scott Junior is worth: 100%=$150, 90%=$110, 60%=$80 Mfg late 1940s to late 1960s.