I had the same problem being locked out of neutral with my 1800 VTX purchased used last year. The bike only has 5100 miles on it. However, I found that just adjusting the linkage only solved the problem temporarily. I would recommend bleeding your clutch fluid in addition to adjusting and lubricating your linkage. Over time, the clutch fluid, if your bike sits for a while without use like mine did, or you don't change the fluid every year, will break down and sludge is left in the bottom of the reservoir and it gets in the system. It looks light brown, thick and slimy. When you change the fluid, start by soaking up the fluid and sludge in the reservoir. Then clean the bottom out with paper towel and a Q tip. This way, you don't suck more sludge through the system during the bleeding process. I use an OTC Bosch vacuum bleeder with my compressor between 80 lbs and 130 lbs.. Some people use a Mityvac. It's cheaper but the take up reservoir is too small for this job. It gets damaged and will fail if the reservoir gets overfilled and brake fluid gets in the pump mechanism.
As you remove fluid, be sure to add fluid from a freshly opened brake fluid. I use Valvoline DOT 3 &4 brake fluid. Don't empty the reservoir completely on vacuum to prevent air from getting int the line. The compressor assisted vacuum bleeder makes the process really quick and clean. Remember brake fluid is very corrosive. It eats paint for lunch! Cover your bike before staring the job. It's worth it. The most careful person can make a mistake and this is an expensive one.
Since completing the clutch bleeding process after the linkage adjustment, I haven't had the lock out problem since and my shifting is like new.
I hope this writing will help someone who is having a similar problem.