Big Jim and Jeff. In the world of carbys, the AMAL Monobloc has to be one of the simplest to set up and maintain. Taking one to bits is straightforward, with plenty of workshop detail available. The most difficult aspect is removing the jet block from the body, but warming the body and gentle persuasion will do it.
As a first step I would identify what you have and compare with what you should have. All the details are here on the Forum, just a case of searching. Has the bike got the right carb, with the right jets, needle and slide? The main jet simply unscrews from the needle jet, which itself unscrews from the jet block. Sediment will collect under the main jet and can give partial blockage and poor running, with the lower cap removed these can be checked without removing the carb from the engine. Just catch the fuel as it drains out. Lowering the needle in the slide will give a weaker mixture. The top retaining ring will unscrew with a bit of luck and the slide, needle and choke assembly pull out. Make sure all the gaskets and fibre washers are present and correct. The fuel level in the float chamber can be easily checked, forum postings tell how. Take great care on re assembly, as threads in the soft Mazac alloy castings are easily damaged by cross threading.
There is a single mesh filter in the fuel inlet banjo, but adding cheap inline filters to each fuel line is a good idea. Changing the carb is a bit drastic, even mix'n'match parts can be made to perform reasonably well and produce a reliable unit.
Swarfy.
