I put a new handle on, took nothing else apart reassembled it and now it only has one speed, nothing seems to be out of place or disconnected?

You need to either re-time the speed control switch at the back or replace it. If it worked great before then it is just an adjustment to get it back to running correctly. YouTube viseo available for timing the switch

I took mine apart completely and reassembled everything and greased everything and mine is doing the same thing. I'm thinking, also, that it is the tightening of the top lock nut.

The screws are roughly 8 turns in from fully out when starting to set the speed. On the lowest speed 13 revolutions of the planetary in 15 seconds is a good speed.

I don't have a direct answer for you. There are many things which could cause the noise from a beater simply hitting the bowl to internal gear problems. You did not say which model you have so take a look at the two Service Manuals linked below. One of these ought to cover your machine.

http://www.kitchenaidparts.eu/documents/pdf/service-manual/classic-svc-manual-new-email-version.pdf

http://ep.yimg.com/ty/cdn/mendingshed/kitchenaid6qtservicemanual.pdf

First dissconnect the power supply.Next, the locking hook must be facing towards the back of the unit. However the lever itself must be placed inside the bottom portion of the unit going out to the side. Next you need to connect the metal link to the lever and UNDERNEATH the locking hook. Once you have done this you can now put the screw in to hold down the lever. Your one speed problem could be caused by the adjustment screws that are connected to the main board at the bottom. if these are not set correctly and most importantly EVENLY the mixer wont operate correctly. The next possible solution is that the main control board is faulty and would have to be replaced part number for the board is w10119326. Also I have added this link from Whirlpool that you can use. Hope this helps. Thanks
http://www.whirlpoolparts.ca/parts/fspShow.php?model=KSM150PSWH0

Yes it is compatible. You may also have a problem with the control plate

For mixmaster junior, but should be relevent to many old sunbeams:

That's not the power cord going to the speed switch. You don't need to get those screws off.
To replace the cord:
Cut the old power cord near where it enters the blender.
remove the two front screws, pull off front housing.
remove 1/4" nuts found in recesses of exposed front plate.
pull speed handle out far enough to get a screwdriver under exposed front plate, and pry gently. It'll come off as it's a friction fit.
cooling fan blade is now visible, you need to remove it.
pry up gently on the teeth attaching it to the motor shaft.
Work your way around the 4 sets of teeth, it'll come off. Don't lose the two washers.
unscrew the electrical contacts.
take off the speednuts holding the brush assembly in place.
gently pull up on the brush assembly with a needle nose, until it comes out.
now remove the screws holding the motor coils in place. They're the same ones the speednuts attached to, and have hex heads you can get at with a needlenose.
once those are out, pull on the motor coils gentle, and wiggle them out of the housing.
You'll see the stub of the old power cord at the back of it.
Get a round replacement wire of the right diameter, thread it through the cord hole in the blender, and connect it up to the coils.
-I had to drill the power cord hole 1/16" larger than it was to get a modern cord to fit through it.
On the stub of the old cord, you'll see a metal ring which serves to anchor the cord in blender body. remove it (screwdriver + needlenose and pry), and attach to new cord at the righ position.
Put everything back together, being careful not to bust the carbon brushes.
Congrats, you now have a functional blender with a cord that won't try to electrocute you.

You can remove the handle-back by gently prying the rear clips down and away. But the problem is the power boost button; it has a fork that goes down the left side and snaps over a micro-switch. You need to get that off since there is not room for all 3 buttons (eject, variable speed, and boost) to slide through the handle. A small probe inserted from the top and pushing on the left side to the rear might do it. Or just pry the boost switch upwards; that's how I got mine apart. My problem was the boost microswitch was bad and provided a poor connection. As a result, the beater only ran intermittently on regular switch positions. I solved it by bypassing the boost micro switch. The beater now only runs on the regular speeds but that's fine by me.

Good luck!

your problem sounds like the thermister is burnt out.