My husqvarna 61 will only run if choke is at least half on

SOURCE: what year was my Husqvarna 61 #5450433 made?

I got this directly from Husky
HusqvarnaUSA.com
http://www.husqvarna.com/us/homeowner/support/download-manuals/
Enter the 3 digit model number (no XPs, Es, just the numbers)
Serial number decode – useful when downloading IPLs and Manuals
06 1500198
06 = year produced – 2006 (single digit before 2000)
15 = week produced - March
00198 = 198th unit Husky produced that week

With your serial
It was the 433 Husky product produced;
The 45th week of;
19- 75, 85, or 95. Contact them. Black on silver or silver on black on the serial tag is one way to verify age but it is my ability to provide an informed answer.
HusqvarnaUSA.com Contact Us
http://www.husqvarna.com/us/homeowner/support/customer-support/
HTH
Lou

SOURCE: i have a husqvarna 455 rancher that won't run at

Clean or replace the fuel filter. Check the fuel lines for decay or other damage. Check the muffler for plugging of the screen. Be sure to run with fresh fuel mix and to shake the container thoroughly each time just before filling the tank to prevent oil starvation. Hope this helps!

SOURCE: I have a husqvarna model

Fuel starvation, replace the fuel filter in the tank, check the fuel hose up to the carb, pay special attention to where it leaves the tank as they do perish, failing this then there is dirt in the carb.

SOURCE: Cannot find adjustment oil screw on my Husqvarna 61 Chainsaw

The 61 has a 4 position oil pump, the adjuster is a black plastic screw located to the top right hand corner of the pump face, just behind the sprocket, you will have to clean around that area to find it. The pump has numbers 1 to 4 around the screw, 4 being the highest position.