Long time competition B/G flier here...the "death spiral" is a spin condition, caused when the inside wing loses lift since it is flying slightly slower and stalls first. if you have weight on the inside (of the turn) wing, definitely take it off, the weight is pro-spin. You want to make aerodynamic adjustments instead.
Washout (up warp NOT down) on the wing tips is very helpful since reduces the angle of attack of the wingtip, causing it to resist dropping by not stalling as soon. Warping the inside tip down is the wrong thing as it causes the tip to stall sooner and thus is also pro-spin. it may seem like it helps a little but, but it makes the wing drop more abrupt and severe (BTW that is how you intentionally spin an airplane using opposite aileron and rudder).
Put in the circling turn with stab tilt, which provides a small yaw force rather than roll. To get a left turn (suitable for right handed toss), tilt the right side of the stab (as seen from the rear) up several degrees. Remember that the aero force on the stab is downward, so the yaw component is backwards from what you'd expect.
Having enough dihedral is crucial; it provides roll stability by decreasing the lift of the "up" wing and increasing the lift of the "down" wing when the glider rolls.
Also check the stab incidence. If it's negative (raising the tail and pushing the nose down) the glider will always nosedive (severe) or spin (subtle).
There's a ton of great information on
https://www.amaglider.com/ . I'd recommend that anyone interested in flying gliders should inhale that site totally.
There is a simple but very good explanation of building HLG's here:
https://f4bscale.worldonline.co.uk/building.htm . The website look-n-feel is awful but the info is great. Take note of the instructions for sanding washout into the wings. You should be able to retrofit your glider even if already built.
