The plutonium was supposed to be melted into an unusable shape, but I'm not sure if they have done this or not.
The 'pit' is only the plutoum part of the bomb, there are many other components needed to make an operational bomb. Such as :

• Kryton switches - needed to time the detonation of the high explosives surrounding the pit.
  
• The HE lenses are also critical to detonation. These have to be precisely machined to form a spherical implosion shockwave. They normally use 2 different types of HE with different detonation velocities so as to curve the implosion around the pit.
  
• Neutron guns are also important to form a full yield.
  

Russia does have far more plutonium than the US. This is largely due to the Soviet policy of producing more plutonium rather than recycling it for new weapons as is western practice. This follows the long practiced Soviet military doctrine of never throwing anything away ie. they still had WW2 tanks and artillery in sheds in the late 80's.
So. most of the Soviet weapons over 15 years old would be unreliable especially their fusion weapons. This is because the form of hydrogen used - deuterium - has a relativlely short half life decaying into helium 3 ( I think ). The US recycles deuterium by passing the it through paladium which removes the helium 3, thus ensuring relablity of the set yield. The Soviets/Russians however do not do this, thus substantially increasing the chances of a ' fizzle '.