There are many other causes for increased fuel consumption such as a clogged air filter, fouled spark plugs, defective spark advance unit, low tire pressures, etc. But if you really think the carb needs an overhaul, you can actually just do it yourself. Just buy a repair kit (including jet/s, and accelerator plunger or diaphragm). But if youre not a DIY'er, then I guess you have no recourse but to take the car to the local talyer and have it done there.
Before deciding finally on overhauling your carburetor and taking it apart, why not consider using one of those aerosol carb cleaners. I've seen it used on my EL 95, and I was pretty much impressed at how much dirt it removed. My gas consumption likewise improved. Just my ten cents.