Hi Biffo. You have not said whether or not your gun is an ejector - this may affect the repair carried out, depending on the type of mainspring that is used in your shotgun. Having repaired many guns in this situation, there are normally three problems affecting a misfire ( excluding cartridges which are generally not at fault ). First and second as most people will point out are a broken spring or striker. The third problem arising may be a broken sear. To ascertain whether or not you have either of first two problems, try this simple diagnosis. In the gun trade, we employ the '' Penny Test''. Having opened your gun and cocked the action, close it and remove the forend. Next, take off the forend and remove the barrels. Holding the stock and action vertically at waist height, so that the face of the action is facing upwards ( you may want to do this outside rather than knocking holes in your kitchen ceiling ) place a two pence coin over the striker hole and fire the corresponding trigger. If the coin hits the ceiling ( or near enough ) then you should have sufficient blow to fire a cartridge. If the striker nose is not protruding through the action face afterwards, then you know that you will almost certainly need a new ( or repaired hammer ), if the spring is at fault you may still have enough blow to dent the cartridge primer but not fire it. Sometimes, if the sear is broken or the ''bent'' on the hammer is worn, you will get a spongey hammer blow or no lift of the 2p coin. Generally speaking, a new mainspring is a fairly simple job to replace and time. A new hammer, or repaired hammer ( sharp intake of breath ) could ultimately cost more than the resale value of the gun itself. Depending on the ejector system employed, this will also dictate the type of mainspring that will need to be replaced and also the rising costs involved. Until the gun is examined properly it would be unfair to point the finger at one problem - there are few English boxlocks with firing pins and disc set strikers - the vintage of your gun would intimate the standard trade gun with a hammer and its integral striker nose. If you were closer to Worcestershire I could help you more!!! Anyway, you can try the penny test, and you will atleast be able to decide before taking your gun in for repair whether or not it is a spring replacement or hammer/striker repair. What you must remember, is that there are no spare parts for these guns, sat packaged waiting at wholesalers. Any repairs will no doubt be costly as a dealer will no doubt pass this job on to a gunsmith and then add their own profit mark up. Please let me know how you get on? - I hope you able to sort this out swiftly as it is not really a major repair to carry out !! But be warned, it could be costly as the work involved will require a gunsmith ( which may mean your gun is sent to trade worker for repair - incurring costs ) and bench time - it wont just involve swapping replacement packet parts like most modern OU's!!! regards, Jim.