This is only my humble opinion from personal experience. I am going to assume there are no alignment problems or rim bumps or nicks. These are a common problem of brake problems and "shimmy" when applying brakes as are worn or old or hard brake pads.. Another problem can be the result of poorly adjusted hub bearings. I prefer the brakes be slightly toe-in. This seems to result in a smoother application of brakes. As specifically to Mafac brakes. I have used a stiffener that was once available that spanned the two front pivot bolts. It is crescent shaped in the same arc as the back mounting plate. The result there was boxing in the pivots front and rear to avoid bolt or mount flex.
I looked at that sunrace derailleur and certainly agree. The box is very much like seventies Shimano packaging. The design and cosmetics with faux engraving look very much like the old 600 rear derailleur. It is less like the Titleist because it lacks the plastic pieces of the Titleist that preceded the Crane and was eventually followed by the Dura Ace and the 600.
I am still following the source of an Ital Sport. I now know this was the name of an Univega model. Is it possible that this was another inhouse brand name used by Lawee at the time of Ital Vega to Univega?
To the fellow that wanted a picture of a gold plated Lambert. I took some pictures. They are not terrific because the bike is hanging up high. I also took some other pictures of various bikes in the same place. I will try to get them downloaded from my camera to email to you.
I recall someone seeking a modern style chainring larger tooth number of 110 bcd? I may have one. let me know. $5 plus mailing (certainly not more than $5) for $10 total.
Happy Trails, John Strizek
Sacratomato CA, USA