Huskylock 535D, The lower looper arm broke prior to me getting machine. Bought a new one, how close to needles should this run, also how close should lower looper and upper looper run , in relation to the eyes of the needles, when stroke is up and at bottom of stroke ? Thanks

http://manuals.husqvarnaviking.com/VSM/Husqvarna%20Viking/HVManual.nsf/1fd5659e6f37141041256697003e64c0/d8e7e6f871334eca852575ed0075b70e/$FILE/Huskylock%20435-435C435D%20x%20.PDF

https://www.sewingpartsonline.com/husqvarna-viking-535d-serger-machine-parts.aspx

you have to make sure the looper is properly positioned. With the screw loosened slightly you should be able to move the looper up and down slightly, thus adjusting the timing. You are looking for the lower looper tip to come in slightly above the needle eyes, as close as possible without touching. Then the upper looper must come in right behind the lower looper "head" as close as possible without touching. The upper looper should then extend past the left needle by about 2-2.5mm, and the needles will come down before the eye of the upper looper returns to the right.

un thread your needles before threading the Lower looper. thread lower looper, then thread needles and your good to go

try calling a sewing machine repair shop and see if they have any

You may need to take it for service. However, since it is an older machine, it may be difficult or impossible to repair.

Loosen the upper tension looper thread by turning the dial to a lower number. The upper tension looper is to tight and pulling the lower looper thread up. Also might want to loosen or tighten the left or right needle tensions depending on the results you get. It will be a trial and error exercise to get the correct adjustment between the loopers and needle thread tensions. Otherwise, you might want to take it to an authorized husqvarna viking dealer for service. You can locate a dealer near you by visiting the husqvarna viking website and clicking on the Dealer link on the left-hand side of the page - http://www.husqvarnaviking.com

Good luck.

You will find that it was most likely the top looper has moved to the left too far, undo the looper clamp and press the looper to the right by about 3mm. Then turn the machine over to see if it still hits anything, when the top looper comes up past the bottom looper there should be about 0.5mm clearance between the two. Try this first please.
Also the arm shaft may have moved. Trace the shaft back to where there is a clamp type crank with usually a hexagon head clamp screw. Loosen this and set the top looper so as the eye of it is just past the needle when it is all the way up and to the left.
You are correct in not using the machine under power, turn by hand when you think it is correct and make sure there is nothing hitting.

the eyes of the needles must line up with lower looper as they pass (timing) the distance between the needle and the looper must be exact. No distance between them and not touching. yep, that tight. they shouldnt move the needle even the slightest amount as they pass each other, yet no space between them.
Kent

Solution taken from "Handbook for Huskylock Sewing Machine Models 1001L/1000L/1000"

1. Raise the presser foot by using presser foot lever. When the presser foot is raised, the two thread tension discs in the thread tension control panel are released so that thread passes freely between them. Otherwise thread tension may not be correct.

Important! When threading the needle, always be sure to lift the presser foot lever, and also take care to thread in the proper order.

Threading order:
1. Upper looper thread (green)
2. Lower looper thread (blue)
3. Double chain stitch looper thread (purple) in case of 5 thread stitch or double chain stitch
4. Right needle thread (red)
5. Left needle thread or double chain needle thread (yellow)

Caution!
Because the left thread tension dial (yellow) is used for either the left needle or the double chain stitch needle, these needles will never be used at the same time.

Upper looper (green) sequence:
1. Thread holder (silver triangle openings attached to thread holder stand)
2. Thread guide (flat silver clips just behind thread tension disc)
3. Thread tension disc (circular knobs with numbers for tension setting)
4. Pull thread around upper looper guide and upper looper
5. Pull thread into hole of upper looper

Lower looper (blue)
Repeat 1, 2, 3.
4. Pull thread around guide (see color coded chart inside front serger cover).

Easy threading mechanism (for lower looper)
1. Pull out the lower looper threading lever
2. Thread the lower looper and position the thread on hook of the lower looper
threading lever.
3. Push the lower looper threading lever back to its basic position while
holding the end of the thread.

Caution:
When returning the lower looper threading lever, always make sure that the two
blue triangle marks (directional arrows) meet each other.

Right needle thread (red)
Left needle thread (yellow)
Important: Thread the needles after threading of lower looper and upper looper.
First raise the presser foot lever, and then thread the needle threads in order shown in color coded thread guide.

yes, take all threads out, and re=thread according to the diagram, following the threading order.