Yes it is the a arm and bulk head bushings that are prone to wear.
I just finished replacing mine with oilite bushings from Ulmer Racing.
From what I have read the stock plastic bushings wear out in and around 500 miles.
The oilites are a kind of metal and from, what I have read do not wear.
The install is real easy,just lots of under hood things that need to be taken off from under the hood to unbolt the a arms.
There are also steering bushings that are often in need of replacing. You will know if the steering has a lot of play in it. OFT Racing makes some nice aluminum with oilite bushing replacements. There are three, two on the steering shaft below the handlebars and one up front by the oil reservoir.
Put the oilites in the steering and a arms. When they warm up they release tiny droplets of oil and keep everything moving nice and smooth with no play. When you first put them in it feels real stff but it loosens up in about 5 miles of riding.