Elderflower wine stuck fermentation

[zamo27]

I did elderflower wine from cordial, diluted down to taste with water and pitched wlp775 champagne yeast
It's been 7weeks and the gravity only went down to 1070. There was lots of airlock activity but gas now stopped
I have thiamin tables I want to add to boost the yeast
Now there's silva, stearic acid and magnesium stearate in the composition of these tablets

Will these help or further damage the yeast?
View attachment ImageUploadedByHome Brew1441103179.939856.jpg

 

[Yooper]

It won't help. It might hurt.

What did the OG start out? What was in the "cordial"?

 

[zamo27]

Elderflower sugar lemon . That's the cordial. How can I reboots the yeast , do a starter and pitch more? There was airlock activity when it started fermentation but it stopped

 

[Yooper]

Elderflower sugar lemon . That's the cordial. How can I reboots the yeast , do a starter and pitch more? There was airlock activity when it started fermentation but it stopped

You used just sugar, elderflowers, and a squeeze of lemon? What was the OG?

 

[zamo27]

1090

 

[Yooper]

1090

Can you post your recipe? If there is too much lemon, it would make the must too acidic for the yeast, whether nutrients are added or not.

it's just impossible to guess without knowing the yeast strain, the recipe, other ingredients, etc. It's not easy to help when we're playing 20 questions.